0001193125-26-065179 | 10-K | XBRL Viewer | Apellis Pharmaceuticals INC

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Income Taxes - Components of Net Income (Loss) From Continuing Operation Before Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
United States	$ (120,516)	$ (22,701)	$ (48,495)
Foreign	144,626	(174,015)	(478,001)
Net income/(loss) before taxes	$ 24,110	$ (196,716)	$ (526,496)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details

Inventory (Tables)

12 Months Ended

Dec. 31, 2025

Inventory Disclosure [Abstract]

Schedule of Inventory

The Company’s inventory of EMPAVELI and SYFOVRE consisted of the following as of December 31, 2025 and 2024 (in thousands):


	December 31,
	2025		2024
Raw materials	$	43,290	$	54,385
Semi-finished goods		121,207		92,872
Finished goods		13,018		9,860
Total inventories	$	177,515	$	157,117

Basis of Presentation and Summary of Significant Accounting Policies	12 Months Ended
Dec. 31, 2025
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	2. Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”). Revenue Recognition The Company’s revenues consist of product sales of EMPAVELI and SYFOVRE and revenue derived from its collaboration arrangement with Sobi. See Note 10, License and Collaboration Agreements for further discussion related to the Sobi Collaboration Agreement. The Company accounts for contracts with its customers in accordance with ASC Topic 606, Revenue from Contracts with Customers, (“ASC 606”). Pursuant to ASC 606, for arrangements or transactions between participants determined to be within the scope of the contracts with customers guidance, the Company performs the following five steps to determine the appropriate amount of revenue to be recognized as the Company fulfills its obligations: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. Revenue is recognized when, or as, the Company satisfies a performance obligation by transferring a promised good or service to a customer. An asset is transferred when, or as, the customer obtains control of that asset. For performance obligations that are satisfied over time, the Company recognizes revenue using an input or output measure of progress that best depicts the satisfaction of the relevant performance obligation. Product Revenue The Company’s revenue from net product sales related to EMPAVELI and SYFOVRE are primarily recognized in the United States. The Company sells EMPAVELI and SYFOVRE principally through arrangements with specialty pharmacies (“SPs”) and specialty distributors (“SDs”), who are the Company’s customers. The customers subsequently resell the product to patients and health care providers. The Company applies the ASC 606 five step process discussed above to the contracts with SPs and SDs. Product revenues are recognized when the customers take control of the product, which typically occurs upon delivery to the customers. The Company recognizes revenue from product sales at the net sales price which includes estimates of variable consideration for which reserves are established and reflects each of these as a reduction to revenue. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which the Company is entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from estimates, the Company may need to adjust its estimates, which would affect net revenue in the period of adjustment. The following are the Company’s significant categories of variable consideration: Fees and Patient Assistance Fees Distribution Fees: Distribution fees include distribution service fees paid to SDs based on a contractually fixed percentage of the wholesale acquisition cost (WAC). These fees are directly related to the storage, handling and distribution of product to customers, and are therefore inseparable from the product. Distribution fees are recorded as an offset to revenue based on contractual terms at the time revenue from the sale is recognized. Credit Card Fees: SDs will sell downstream to customers who may pay for product via credit card. The Company will reimburse its SDs for the credit card fees incurred as a result of SDs accepting credit cards as a form of payment from the downstream customers. Credit card fees are recorded as an offset to revenue based on the average aggregate credit card rate as a percentage of SD sales at the time revenue from the sale is recognized. Patient Assistance Copay: Other incentives include voluntary patient assistance programs, such as the Company’s co-pay assistance program, which are intended to provide financial assistance to qualified commercially-insured patients with prescription drug co-payments required by payors. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability. Government, Other Rebates and Chargebacks Rebates Government Rebates: The Company’s products are subject to pricing limits under certain federal government programs. Qualifying entities (i.e., end-users) purchase products from the Company’s customers at their qualifying discounted price. The chargeback amount the Company incurs represents the difference between the Company’s contractual sales price to the customer, and the end-user’s applicable discounted purchase price under the government program. Manufacturer Discount Program: The Company also participates in the Manufacturer Discount program, a federal program where the Company is required to provide discounts on drugs dispensed to eligible Medicare Part D patients. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability. Other Rebates and Chargebacks: The Company contracts with certain organizations, primarily group purchasing organizations ("GPOs") and pharmacy benefit managers, for the payment of rebates with respect to purchase of the Company's products by the end users. The Company estimates these rebates and records such estimates in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability. GPOs purchase from SDs at a discounted price. SDs charge back to the Company the difference between the price initially paid by SDs and the discounted price paid to SDs by the GPOs. The Company issues credit notes for the chargeback which are applied against amounts due from the SD. Returns Consistent with industry practice, the Company offers SPs and SDs limited product return rights for product damaged in shipping or shipped in error, short-dated, expired, recalled, or discontinued products; provided that the return is within a specified period around the product expiration date as set forth in the applicable individual distribution agreement. The Company does not allow product returns for product that has been dispensed to a patient. As the Company receives inventory reports from SPs and SDs and has visibility into the inventory distribution channel, it is able to make a reasonable estimate of future potential product returns based on this on-hand channel inventory data and sell-through data obtained from SPs and SDs. In arriving at its estimate for product returns, the Company also considers historical product returns and the underlying product demand. Licensing and Other Revenue The Company analyzes license and collaboration arrangements pursuant to FASB ASC Topic 808, Collaborative Arrangement Guidance and Considerations, (“ASC 808”) to assess whether such arrangements, or transactions between arrangement participants, involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities or are more akin to a vendor-customer relationship. In making this evaluation, the Company considers whether the activities of the collaboration are considered to be distinct and deemed to be within the scope of the collaborative arrangement guidance or if they are more reflective of a vendor-customer relationship and, therefore, within the scope of ASC 606. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For elements of collaboration arrangements that are not accounted for pursuant to guidance in ASC 606, an appropriate recognition method is determined and applied consistently, generally by analogy to the revenue from contracts with customers guidance. Amounts related to transactions with a counterparty in a collaborative arrangement that is not a customer are presented as collaboration revenue and in a separate line item from revenue recognized from contracts with customers, if any, in the consolidated statements of operations. Pursuant to ASC 606, for arrangements or transactions between arrangement participants determined to be within the scope of the contracts with customers guidance, the Company performs the five-step process discussed above to determine the appropriate amount of revenue to be recognized as the Company fulfills its obligations. The Company evaluates the performance obligations promised in the contract that are based on goods and services that will be transferred to the customer and determine whether those obligations are both (i) capable of being distinct and (ii) distinct in the context of the contract. Goods or services that meet these criteria are considered distinct performance obligations. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each arrangement that includes variable consideration, the Company evaluates the amount of potential transaction price and the likelihood that the transaction price will be received. The Company utilizes either the most likely amount method or expected value method to estimate the amount expected to be received based on which method best predicts the amount expected to be received. The amount of variable consideration that is included in the transaction price may be constrained and is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and, if so, these options are considered performance obligations. The Company has not currently identified any such material rights. Revenue is recognized when, or as, the Company satisfies a performance obligation by transferring a promised good or service to a customer. An asset is transferred when, or as, the customer obtains control of that asset. For performance obligations that are satisfied over time, the Company recognizes revenue using an input or output measure of progress that best depicts the satisfaction of the relevant performance obligation. After contract inception, the transaction price is reassessed at every period end and updated for changes such as resolution of uncertain events. Any change in the overall transaction price is allocated to the performance obligations on the same methodology as at contract inception. Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker (“CODM”) is the chief executive officer (“CEO”). The Company manages its operations as a single operating segment. See Note 16, Segment Information, for additional information. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities in the Company’s consolidated financial statements and the accompanying notes. These estimates are based on historical experience and various other assumptions believed to be reasonable under the circumstances. Such estimates are used in the following areas, among others: accrued research and development expenses, reserves for variable consideration and reserves for excess or obsolete inventories. Actual results may differ from those estimates. Fair Value of Financial Instruments The Company is required to disclose information on the fair value of financial instruments and inputs that enable an assessment of the fair value. The three levels of the fair value hierarchy prioritize valuation inputs based upon the observable nature of those inputs as follows: Level 1 – Quoted prices in active markets for identical assets or liabilities; Level 2 – Inputs other than quoted prices included within level 1 that are observable for the asset or liability, either directly or indirectly; Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. The Company’s financial instruments, in addition to those presented in Note 7, Long-term Debt, and Note 9, Fair Value Measurements, include cash and cash equivalents, accounts payable and accrued liabilities. Management believes that the carrying amounts of cash and cash equivalents, accounts payable and accrued expenses approximate the fair value due to the short-term nature of those instruments. Cash and Cash Equivalents The Company considers highly-liquid investments with original maturities of three months or less to be cash equivalents. The Company holds cash in highly-liquid bank accounts and invests excess cash in money market funds. Accounts Receivable The Company’s accounts receivable are inclusive of receivables from its product sales to customers. They are generally stated at the invoiced amount and do not bear interest. The accounts receivable from product sales represent receivables due from the Company’s SPs or SDs. Payment terms are generally 30-65 days for EMPAVELI and 60-150 days for SYFOVRE. The Company monitors the financial performance and creditworthiness of its customers and provides reserves against trade receivables for expected credit losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are written-off against the established reserve. As of December 31, 2025 and 2024, the Company did not have an allowance for credit losses. The Company has had no historical write-offs of its accounts receivable as of December 31, 2025 and 2024. The Company has an agreement (the “Factoring Agreement”) to sell certain trade accounts receivable to a third-party financial institution at a discount to the invoiced amount. Under the Factoring Agreement, the maximum amount of outstanding accounts receivables sold at any time is $100.0 million. The Company accounts for the transfer of trade accounts receivable under the Factoring Agreement as a sale in accordance with ASC 860, Transfers and Servicing, because effective control and risk associated with the transferred accounts receivable is passed to the third-party. Accordingly, the Company derecognizes the sold trade accounts receivable from the consolidated balance sheets. Cash proceeds related to the accounts receivable sold are included in cash from operating activities in the consolidated statements of cash flows. Any discounts or fees incurred in connection with the sales are recorded within “Selling, general and administrative expenses" in the consolidated statements of operations and comprehensive income/(loss). Pursuant to the Factoring Agreement, the Company performs certain collection and administrative functions for the receivable sold. The fair value of these administrative services is not material and therefore, the Company has not recorded any servicing assets or liabilities associated with the Factoring Agreement. See Note 3, Product Revenues, Accounts Receivable, and Reserves for Product Sales for additional information. Inventory Inventory is recorded at the lower of cost or net realizable value, with cost determined on a first-in, first-out basis. Inventory costs include third-party contract manufacturing, third-party packaging services, labor, overhead and freight. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and writes down any excess and obsolete inventories to their estimated realizable value. Expenses incurred related to excess and obsolete inventories are recorded within cost of sales. The determination of whether inventory costs will be realizable requires estimates by management. Provisions for potentially obsolete or slow-moving inventory are made based on the Company’s analysis of product dating, inventory levels, historical obsolescence and future sales forecasts. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required which would be recorded as a cost of sales in the consolidated statements of operations and comprehensive income/(loss). Inventory not expected to be sold within the Company’s normal operating cycle is classified as long-term inventory on the consolidated balance sheets. Prior to regulatory approval of its product candidates, the Company expenses costs associated with the manufacturing of its product candidates to research and development expense unless the Company is reasonably certain such costs have future commercial use and net realizable value. When the Company believes regulatory approval and subsequent commercialization of its product candidates is probable, and the Company also expects future economic benefit from the sales of the product candidates to be realized, the Company will then capitalize the costs of production as inventory. Inventory that can be used in either the production of clinical or commercial product is expensed as research and development expense when selected for use in a clinical manufacturing campaign. Shipping and handling costs for product shipments are recorded as incurred in cost of sales along with costs associated with manufacturing the product and any inventory write-downs. Foreign Currency The functional currency of each of the Company’s subsidiaries is its local currency, except for the wholly owned subsidiaries Apellis Europe B.V. and Apellis International GmbH where the functional currency is the U.S. dollar. Revenues and expenses of the subsidiaries have been translated into U.S. dollars at average exchange rates prevailing during the respective periods. Assets and liabilities have been translated at the rates of exchange on the balance sheet date. The resulting translation gain and loss adjustments are recorded directly as a separate component of stockholders’ equity. Research and Development Costs incurred in connection with research and development activities are expensed as incurred. Research and development expenses include (i) employee-related expenses, including salaries, benefits, travel and share-based compensation expense; (ii) external research and development expenses incurred under arrangements with third parties, such as contract research and contract manufacturing organizations, investigational sites and consultants, including share-based compensation expense for consultants; (iii) the cost of acquiring, developing and manufacturing clinical study materials; and (iv) costs associated with preclinical and clinical activities and regulatory operations. The Company enters into consulting, research and other agreements with commercial entities, researchers, universities and others for the provision of goods and services. Such arrangements are generally cancellable upon reasonable notice and payment of costs incurred. Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided by the Company’s clinical sites and vendors. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly. Under the Sobi Collaboration Agreement, the Company may receive reimbursements from Sobi for certain agreed upon developmental activities. The Company presents such reimbursements as contra-research and development expense based on an evaluation of the nature and contractual terms of the arrangement and the nature of the Company’s business operations. Selling, General and Administrative Costs incurred in connection with selling, general and administrative activities are expensed as incurred. Selling, general and administrative expenses consist primarily of costs associated with the commercialization of approved products and general and administrative costs to support operations, including salaries, bonuses, benefits and share-based compensation. Selling expenses include product marketing, sales operations costs, and other costs incurred to support the Company’s sales efforts. General and administrative expenses include corporate support functions such as executive management, finance and accounting, business development, legal, human resources, information technology, and associated external costs to support those functions. Other significant costs include costs associated with medical affairs, drug safety and pharmacovigilance, quality and regulatory costs not otherwise included in research and development expenses, legal fees relating to patent and corporate matters, and fees for accounting and consulting services. Marketing and advertising costs include marketing literature, promotional activities, conferences and seminars, branding and sponsorships. For the years ended December 31, 2025, 2024 and 2023, the Company incurred advertising costs of $91.8 million, $83.3 million, and $86.5 million, respectively. Income Taxes The provision for income taxes includes federal, state, local and foreign taxes. Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions using a more likely than not threshold for recognizing and resolving uncertain tax positions. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of December 31, 2025 and 2024, the Company did not have any significant uncertain tax positions Share-Based Compensation The Company’s share-based compensation program allows for grants of stock options and restricted stock units. The Company measures share-based compensation cost at the grant date based on the fair value of the option and restricted stock units, and recognizes the expense related to awards on a straight-line basis over the requisite service period, which is typically the vesting period. Expense for awards with performance conditions is estimated and adjusted on a quarterly basis based upon the assessment of the probability that the performance condition will be met, and is expensed using an accelerated method over the term of the award. Forfeitures are recognized as they occur. The Company estimates the fair value of each option using the Black-Scholes option pricing model that considers the fair value of its common stock, the exercise price, the expected life of the option, the expected volatility of its common stock, expected dividends on its common stock, and the risk-free interest rate over the expected life of the option. The Company uses the simplified method described in the SEC’s Staff Accounting Bulletin No. 107, Share-Based Payment, to determine the expected life of the option grants. The estimate of expected volatility is based on the Company’s historical volatility over a period commensurate with the expected term of the option. The Company has never declared or paid any cash dividends on its common stock and does not expect to do so in the foreseeable future. Accordingly, it uses an expected dividend yield of zero. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant valuation for a period commensurate with expected term of the option. Additionally, the Company uses a Monte Carlo simulation model to calculate the estimated fair value on the date of grant related to awards with market-based conditions. For awards with performance conditions, the Company assesses the probability of achievement at each reporting date to determine recognition of compensation expense. Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk include cash and cash equivalents and accounts receivable. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and the issuers of its cash equivalents. The Company maintains its cash and cash equivalents with highly-rated financial institutions. At times, such amounts may exceed federally-insured limits. The Company has not experienced any losses on its deposits since inception, and management believes that minimal credit risk exists with respect to these financial institutions. Billings to large specialty pharmacies and specialty distributors account for the majority of the Company’s accounts receivable, and collateral is generally not required from these customers. To mitigate credit risk, the Company monitors the financial performance and credit-worthiness of its customers. See Note 3, Product Revenues, Accounts Receivable, and Reserves for Product Sales for additional information. Net Income/(Loss) per Share Basic net income/(loss) per share is calculated by dividing the net income or loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net income/(loss) per share is computed by dividing the net income or loss by the weighted-average number of shares of common stock, plus potentially dilutive securities outstanding for the period, as determined in accordance with the treasury stock, if-converted, or contingently issuable accounting methods, depending on the nature of the security. For purposes of the diluted net income/(loss) per share calculation, stock options, restricted stock units (“RSUs”), shares potentially issuable in connection with the Company’s employee stock purchase plan (“ESPP”) and convertible notes are considered potentially dilutive securities and included to the extent that their addition is not antidilutive. Recent Accounting Pronouncements issued not yet adopted In December 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2025‑12, Codification Improvements, which includes targeted amendments to clarify, correct, and improve various aspects of the FASB Accounting Standards Codification. The ASU is effective for annual periods beginning after December 15, 2026, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements. In December 2025, the FASB issued ASU 2025‑11, Interim Reporting (Topic 270): Improvements to Interim Disclosure Requirements, which clarifies disclosure requirements for interim financial statements. The ASU is effective for interim reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the impact of this guidance on its interim financial statement disclosures. In September 2025, the “FASB issued “ASU 2025-06, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Improvements to Capitalization of Software Development Costs, which updates the accounting guidance for internal-use software costs and removes references to prescriptive project stages. The ASU is effective for annual periods beginning after December 15, 2027, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the timing of adoption and the impact of the new guidance on the consolidated financial statements and related disclosures. In July 2025, the FASB issued ASU 2025-05, Measurement of Credit Losses for Accounts Receivable and Contract Assets, which provides a practical expedient to measure credit losses on accounts receivable and contract assets. The ASU is effective for annual periods beginning after December 15, 2025, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the timing of the adoption and the impact of the new guidance on the consolidated financial statements and related disclosures. In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, which requires additional disclosure of the nature of expenses included in the income statement. The standard requires disclosures about specific types of expenses included in the expense captions presented in the income. This ASU is effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027, with early adoption permitted. The requirements should be applied on a prospective basis while retrospective application is permitted. The Company is currently evaluating the impact that the adoption of this guidance will have on its disclosures. Recently adopted accounting pronouncements In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures. This standard is an amendment to the accounting guidance on income taxes which establishes incremental disaggregation of income tax disclosure pertaining to the effective tax rate reconciliation and income taxes paid. The amendments in this update are required to be applied on a prospective basis with the option to apply it retrospectively. The guidance is effective for annual periods beginning after December 15, 2024. The Company adopted ASU 2023-09 for the year ended December 31, 2025, and applied the new disclosure requirements retrospectively to the current annual period. The adoption of this standard did not have a material impact on the Company's consolidated financial position or results of operation. Refer to Note 12, Income Taxes in the accompanying notes to the consolidated financial statements for further details.

Basis of Presentation and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Basis of Presentation and Summary of Significant Accounting Policies

2. Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”).

Revenue Recognition

The Company’s revenues consist of product sales of EMPAVELI and SYFOVRE and revenue derived from its collaboration arrangement with Sobi. See Note 10, License and Collaboration Agreements for further discussion related to the Sobi Collaboration Agreement.

The Company accounts for contracts with its customers in accordance with ASC Topic 606, Revenue from Contracts with Customers, (“ASC 606”). Pursuant to ASC 606, for arrangements or transactions between participants determined to be within the scope of the contracts with customers guidance, the Company performs the following five steps to determine the appropriate amount of revenue to be recognized as the Company fulfills its obligations: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation.

Revenue is recognized when, or as, the Company satisfies a performance obligation by transferring a promised good or service to a customer. An asset is transferred when, or as, the customer obtains control of that asset. For performance obligations that are satisfied over time, the Company recognizes revenue using an input or output measure of progress that best depicts the satisfaction of the relevant performance obligation.

Product Revenue

The Company’s revenue from net product sales related to EMPAVELI and SYFOVRE are primarily recognized in the United States. The Company sells EMPAVELI and SYFOVRE principally through arrangements with specialty pharmacies (“SPs”) and specialty distributors (“SDs”), who are the Company’s customers. The customers subsequently resell the product to patients and health care providers. The Company applies the ASC 606 five step process discussed above to the contracts with SPs and SDs. Product revenues are recognized when the customers take control of the product, which typically occurs upon delivery to the customers.

The Company recognizes revenue from product sales at the net sales price which includes estimates of variable consideration for which reserves are established and reflects each of these as a reduction to revenue. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which the Company is entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from estimates, the Company may need to adjust its estimates, which would affect net revenue in the period of adjustment. The following are the Company’s significant categories of variable consideration:

Fees and Patient Assistance

Fees

Distribution Fees: Distribution fees include distribution service fees paid to SDs based on a contractually fixed percentage of the wholesale acquisition cost (WAC). These fees are directly related to the storage, handling and distribution of product to customers, and are therefore inseparable from the product. Distribution fees are recorded as an offset to revenue based on contractual terms at the time revenue from the sale is recognized.

Credit Card Fees: SDs will sell downstream to customers who may pay for product via credit card. The Company will reimburse its SDs for the credit card fees incurred as a result of SDs accepting credit cards as a form of payment from the downstream customers. Credit card fees are recorded as an offset to revenue based on the average aggregate credit card rate as a percentage of SD sales at the time revenue from the sale is recognized.

Patient Assistance

Copay: Other incentives include voluntary patient assistance programs, such as the Company’s co-pay assistance program, which are intended to provide financial assistance to qualified commercially-insured patients with prescription drug co-payments required by payors. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability.

Government, Other Rebates and Chargebacks

Rebates

Government Rebates: The Company’s products are subject to pricing limits under certain federal government programs. Qualifying entities (i.e., end-users) purchase products from the Company’s customers at their qualifying discounted price. The chargeback amount the Company incurs represents the difference between the Company’s contractual sales price to the customer, and the end-user’s applicable discounted purchase price under the government program.

Manufacturer Discount Program: The Company also participates in the Manufacturer Discount program, a federal program where the Company is required to provide discounts on drugs dispensed to eligible Medicare Part D patients. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability.

Other Rebates and Chargebacks: The Company contracts with certain organizations, primarily group purchasing organizations ("GPOs") and pharmacy benefit managers, for the payment of rebates with respect to purchase of the Company's products by the end

users. The Company estimates these rebates and records such estimates in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability.

GPOs purchase from SDs at a discounted price. SDs charge back to the Company the difference between the price initially paid by SDs and the discounted price paid to SDs by the GPOs. The Company issues credit notes for the chargeback which are applied against amounts due from the SD.

Returns

Consistent with industry practice, the Company offers SPs and SDs limited product return rights for product damaged in shipping or shipped in error, short-dated, expired, recalled, or discontinued products; provided that the return is within a specified period around the product expiration date as set forth in the applicable individual distribution agreement. The Company does not allow product returns for product that has been dispensed to a patient. As the Company receives inventory reports from SPs and SDs and has visibility into the inventory distribution channel, it is able to make a reasonable estimate of future potential product returns based on this on-hand channel inventory data and sell-through data obtained from SPs and SDs. In arriving at its estimate for product returns, the Company also considers historical product returns and the underlying product demand.

Licensing and Other Revenue

The Company analyzes license and collaboration arrangements pursuant to FASB ASC Topic 808, Collaborative Arrangement Guidance and Considerations, (“ASC 808”) to assess whether such arrangements, or transactions between arrangement participants, involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities or are more akin to a vendor-customer relationship. In making this evaluation, the Company considers whether the activities of the collaboration are considered to be distinct and deemed to be within the scope of the collaborative arrangement guidance or if they are more reflective of a vendor-customer relationship and, therefore, within the scope of ASC 606. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement.

For elements of collaboration arrangements that are not accounted for pursuant to guidance in ASC 606, an appropriate recognition method is determined and applied consistently, generally by analogy to the revenue from contracts with customers guidance. Amounts related to transactions with a counterparty in a collaborative arrangement that is not a customer are presented as collaboration revenue and in a separate line item from revenue recognized from contracts with customers, if any, in the consolidated statements of operations.

Pursuant to ASC 606, for arrangements or transactions between arrangement participants determined to be within the scope of the contracts with customers guidance, the Company performs the five-step process discussed above to determine the appropriate amount of revenue to be recognized as the Company fulfills its obligations.

The Company evaluates the performance obligations promised in the contract that are based on goods and services that will be transferred to the customer and determine whether those obligations are both (i) capable of being distinct and (ii) distinct in the context of the contract. Goods or services that meet these criteria are considered distinct performance obligations. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each arrangement that includes variable consideration, the Company evaluates the amount of potential transaction price and the likelihood that the transaction price will be received. The Company utilizes either the most likely amount method or expected value method to estimate the amount expected to be received based on which method best predicts the amount expected to be received. The amount of variable consideration that is included in the transaction price may be constrained and is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and, if so, these options are considered performance obligations. The Company has not currently identified any such material rights.

After contract inception, the transaction price is reassessed at every period end and updated for changes such as resolution of uncertain events. Any change in the overall transaction price is allocated to the performance obligations on the same methodology as at contract inception.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker (“CODM”) is the chief executive officer (“CEO”). The Company manages its operations as a single operating segment. See Note 16, Segment Information, for additional information.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities in the Company’s consolidated financial statements and the accompanying notes. These estimates are based on historical experience and various other assumptions believed to be reasonable under the circumstances. Such estimates are used in the following areas, among others: accrued research and development expenses, reserves for variable consideration and reserves for excess or obsolete inventories. Actual results may differ from those estimates.

Fair Value of Financial Instruments

The Company is required to disclose information on the fair value of financial instruments and inputs that enable an assessment of the fair value. The three levels of the fair value hierarchy prioritize valuation inputs based upon the observable nature of those inputs as follows:

Level 1 – Quoted prices in active markets for identical assets or liabilities;

Level 2 – Inputs other than quoted prices included within level 1 that are observable for the asset or liability, either directly or indirectly;

Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability.

The Company’s financial instruments, in addition to those presented in Note 7, Long-term Debt, and Note 9, Fair Value Measurements, include cash and cash equivalents, accounts payable and accrued liabilities. Management believes that the carrying amounts of cash and cash equivalents, accounts payable and accrued expenses approximate the fair value due to the short-term nature of those instruments.

Cash and Cash Equivalents

The Company considers highly-liquid investments with original maturities of three months or less to be cash equivalents. The Company holds cash in highly-liquid bank accounts and invests excess cash in money market funds.

Accounts Receivable

The Company’s accounts receivable are inclusive of receivables from its product sales to customers. They are generally stated at the invoiced amount and do not bear interest. The accounts receivable from product sales represent receivables due from the Company’s SPs or SDs. Payment terms are generally 30-65 days for EMPAVELI and 60-150 days for SYFOVRE. The Company monitors the financial performance and creditworthiness of its customers and provides reserves against trade receivables for expected credit losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are written-off against the established reserve. As of December 31, 2025 and 2024, the Company did not have an allowance for credit losses. The Company has had no historical write-offs of its accounts receivable as of December 31, 2025 and 2024.

The Company has an agreement (the “Factoring Agreement”) to sell certain trade accounts receivable to a third-party financial institution at a discount to the invoiced amount. Under the Factoring Agreement, the maximum amount of outstanding accounts receivables sold at any time is $100.0 million. The Company accounts for the transfer of trade accounts receivable under the Factoring Agreement as a sale in accordance with ASC 860, Transfers and Servicing, because effective control and risk associated with the transferred accounts receivable is passed to the third-party. Accordingly, the Company derecognizes the sold trade accounts receivable from the consolidated balance sheets. Cash proceeds related to the accounts receivable sold are included in cash from operating activities in the consolidated statements of cash flows. Any discounts or fees incurred in connection with the sales are recorded within “Selling, general and administrative expenses" in the consolidated statements of operations and comprehensive income/(loss). Pursuant to the Factoring Agreement, the Company performs certain collection and administrative functions for the receivable sold. The fair value of these administrative services is not material and therefore, the Company has not recorded any servicing assets or liabilities associated with the Factoring Agreement. See Note 3, Product Revenues, Accounts Receivable, and Reserves for Product Sales for additional information.

Inventory

Inventory is recorded at the lower of cost or net realizable value, with cost determined on a first-in, first-out basis. Inventory costs include third-party contract manufacturing, third-party packaging services, labor, overhead and freight. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and writes down any excess and obsolete inventories to their estimated realizable value. Expenses incurred related to excess and obsolete inventories are recorded within cost of sales. The determination of whether inventory costs will be realizable requires estimates by management. Provisions for potentially obsolete or slow-moving inventory are made based on the Company’s analysis of product dating, inventory levels, historical obsolescence and future sales forecasts. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required which would be recorded as a cost of sales in the consolidated statements of operations and comprehensive income/(loss).

Inventory not expected to be sold within the Company’s normal operating cycle is classified as long-term inventory on the consolidated balance sheets.

Prior to regulatory approval of its product candidates, the Company expenses costs associated with the manufacturing of its product candidates to research and development expense unless the Company is reasonably certain such costs have future commercial use and net realizable value. When the Company believes regulatory approval and subsequent commercialization of its product candidates is probable, and the Company also expects future economic benefit from the sales of the product candidates to be realized, the Company will then capitalize the costs of production as inventory. Inventory that can be used in either the production of clinical or commercial product is expensed as research and development expense when selected for use in a clinical manufacturing campaign.

Shipping and handling costs for product shipments are recorded as incurred in cost of sales along with costs associated with manufacturing the product and any inventory write-downs.

Foreign Currency

The functional currency of each of the Company’s subsidiaries is its local currency, except for the wholly owned subsidiaries Apellis Europe B.V. and Apellis International GmbH where the functional currency is the U.S. dollar. Revenues and expenses of the subsidiaries have been translated into U.S. dollars at average exchange rates prevailing during the respective periods. Assets and liabilities have been translated at the rates of exchange on the balance sheet date. The resulting translation gain and loss adjustments are recorded directly as a separate component of stockholders’ equity.

Research and Development

Costs incurred in connection with research and development activities are expensed as incurred. Research and development expenses include (i) employee-related expenses, including salaries, benefits, travel and share-based compensation expense; (ii) external research and development expenses incurred under arrangements with third parties, such as contract research and contract manufacturing organizations, investigational sites and consultants, including share-based compensation expense for consultants; (iii) the cost of acquiring, developing and manufacturing clinical study materials; and (iv) costs associated with preclinical and clinical activities and regulatory operations.

The Company enters into consulting, research and other agreements with commercial entities, researchers, universities and others for the provision of goods and services. Such arrangements are generally cancellable upon reasonable notice and payment of costs incurred. Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided by the Company’s clinical sites and vendors. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company.

Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly.

Under the Sobi Collaboration Agreement, the Company may receive reimbursements from Sobi for certain agreed upon developmental activities. The Company presents such reimbursements as contra-research and development expense based on an evaluation of the nature and contractual terms of the arrangement and the nature of the Company’s business operations.

Selling, General and Administrative

Costs incurred in connection with selling, general and administrative activities are expensed as incurred. Selling, general and administrative expenses consist primarily of costs associated with the commercialization of approved products and general and administrative costs to support operations, including salaries, bonuses, benefits and share-based compensation. Selling expenses include product marketing, sales operations costs, and other costs incurred to support the Company’s sales efforts. General and administrative expenses include corporate support functions such as executive management, finance and accounting, business

development, legal, human resources, information technology, and associated external costs to support those functions. Other significant costs include costs associated with medical affairs, drug safety and pharmacovigilance, quality and regulatory costs not otherwise included in research and development expenses, legal fees relating to patent and corporate matters, and fees for accounting and consulting services. Marketing and advertising costs include marketing literature, promotional activities, conferences and seminars, branding and sponsorships.

For the years ended December 31, 2025, 2024 and 2023, the Company incurred advertising costs of $91.8 million, $83.3 million, and $86.5 million, respectively.

Income Taxes

The provision for income taxes includes federal, state, local and foreign taxes. Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.

The Company accounts for uncertain tax positions using a more likely than not threshold for recognizing and resolving uncertain tax positions. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of December 31, 2025 and 2024, the Company did not have any significant uncertain tax positions

Share-Based Compensation

The Company’s share-based compensation program allows for grants of stock options and restricted stock units.

The Company measures share-based compensation cost at the grant date based on the fair value of the option and restricted stock units, and recognizes the expense related to awards on a straight-line basis over the requisite service period, which is typically the vesting period. Expense for awards with performance conditions is estimated and adjusted on a quarterly basis based upon the assessment of the probability that the performance condition will be met, and is expensed using an accelerated method over the term of the award. Forfeitures are recognized as they occur.

The Company estimates the fair value of each option using the Black-Scholes option pricing model that considers the fair value of its common stock, the exercise price, the expected life of the option, the expected volatility of its common stock, expected dividends on its common stock, and the risk-free interest rate over the expected life of the option. The Company uses the simplified method described in the SEC’s Staff Accounting Bulletin No. 107, Share-Based Payment, to determine the expected life of the option grants. The estimate of expected volatility is based on the Company’s historical volatility over a period commensurate with the expected term of the option. The Company has never declared or paid any cash dividends on its common stock and does not expect to do so in the foreseeable future. Accordingly, it uses an expected dividend yield of zero. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant valuation for a period commensurate with expected term of the option. Additionally, the Company uses a Monte Carlo simulation model to calculate the estimated fair value on the date of grant related to awards with market-based conditions. For awards with performance conditions, the Company assesses the probability of achievement at each reporting date to determine recognition of compensation expense.

Concentrations of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk include cash and cash equivalents and accounts receivable.

The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and the issuers of its cash equivalents. The Company maintains its cash and cash equivalents with highly-rated financial institutions. At times, such amounts may exceed federally-insured limits. The Company has not experienced any losses on its deposits since inception, and management believes that minimal credit risk exists with respect to these financial institutions.

Billings to large specialty pharmacies and specialty distributors account for the majority of the Company’s accounts receivable, and collateral is generally not required from these customers. To mitigate credit risk, the Company monitors the financial performance and credit-worthiness of its customers. See Note 3, Product Revenues, Accounts Receivable, and Reserves for Product Sales for additional information.

Net Income/(Loss) per Share

Basic net income/(loss) per share is calculated by dividing the net income or loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net income/(loss) per share is computed by dividing the net income or loss by the weighted-average number of shares of common stock, plus potentially

dilutive securities outstanding for the period, as determined in accordance with the treasury stock, if-converted, or contingently issuable accounting methods, depending on the nature of the security. For purposes of the diluted net income/(loss) per share calculation, stock options, restricted stock units (“RSUs”), shares potentially issuable in connection with the Company’s employee stock purchase plan (“ESPP”) and convertible notes are considered potentially dilutive securities and included to the extent that their addition is not antidilutive.

Recent Accounting Pronouncements issued not yet adopted

In December 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2025‑12, Codification Improvements, which includes targeted amendments to clarify, correct, and improve various aspects of the FASB Accounting Standards Codification. The ASU is effective for annual periods beginning after December 15, 2026, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements.

In December 2025, the FASB issued ASU 2025‑11, Interim Reporting (Topic 270): Improvements to Interim Disclosure Requirements, which clarifies disclosure requirements for interim financial statements. The ASU is effective for interim reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the impact of this guidance on its interim financial statement disclosures.

In September 2025, the “FASB issued “ASU 2025-06, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Improvements to Capitalization of Software Development Costs, which updates the accounting guidance for internal-use software costs and removes references to prescriptive project stages. The ASU is effective for annual periods beginning after December 15, 2027, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the timing of adoption and the impact of the new guidance on the consolidated financial statements and related disclosures.

In July 2025, the FASB issued ASU 2025-05, Measurement of Credit Losses for Accounts Receivable and Contract Assets, which provides a practical expedient to measure credit losses on accounts receivable and contract assets. The ASU is effective for annual periods beginning after December 15, 2025, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the timing of the adoption and the impact of the new guidance on the consolidated financial statements and related disclosures.

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, which requires additional disclosure of the nature of expenses included in the income statement. The standard requires disclosures about specific types of expenses included in the expense captions presented in the income. This ASU is effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027, with early adoption permitted. The requirements should be applied on a prospective basis while retrospective application is permitted. The Company is currently evaluating the impact that the adoption of this guidance will have on its disclosures.

Recently adopted accounting pronouncements

In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures. This standard is an amendment to the accounting guidance on income taxes which establishes incremental disaggregation of income tax disclosure pertaining to the effective tax rate reconciliation and income taxes paid. The amendments in this update are required to be applied on a prospective basis with the option to apply it retrospectively. The guidance is effective for annual periods beginning after December 15, 2024. The Company adopted ASU 2023-09 for the year ended December 31, 2025, and applied the new disclosure requirements retrospectively to the current annual period. The adoption of this standard did not have a material impact on the Company's consolidated financial position or results of operation. Refer to Note 12, Income Taxes in the accompanying notes to the consolidated financial statements for further details.

Leases - Maturity of Operating Lease Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Leases [Abstract]
2026	$ 7,940
2027	5,808
2028	3,581
2029	3,324
2030 and thereafter	373
Total future minimum lease payments	21,026
Less imputed interest	(1,992)
Total operating lease liabilities	$ 19,034	$ 16,954

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2025	Feb. 17, 2026	Jun. 30, 2025
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2025
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Trading Symbol	APLS
Entity Registrant Name	APELLIS PHARMACEUTICALS, INC.
Entity Central Index Key	0001492422
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		127,829,909
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 1.8
Entity Current Reporting Status	Yes
Entity File Number	001-38276
Entity Tax Identification Number	27-1537290
Entity Address, Address Line One	100 Fifth Avenue
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	617
Local Phone Number	977-5700
Entity Interactive Data Current	Yes
Security 12b Title	Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Document Transition Report	false
Document Financial Statement Error Correction	false
ICFR Auditor Attestation Flag	true
Auditor Name	Deloitte & Touche LLP
Auditor Firm ID	34
Auditor Location	Boston, Massachusetts
Auditor Opinion	Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of Apellis Pharmaceuticals, Inc. and subsidiaries (the “Company”) as of December 31, 2025 and 2024, the related consolidated statements of operations and comprehensive income/(loss), changes in stockholders’ equity, and cash flows, for each of the three years in the period ended December 31, 2025, and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America. We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company’s internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control—Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated February 24, 2026, expressed an unqualified opinion on the Company’s internal control over financial reporting.
Documents Incorporated by Reference	The registrant intends to file a definitive proxy statement pursuant to Regulation 14A in connection with its 2026 Annual Meeting of Stockholders within 120 days of the end of the registrant’s fiscal year ended December 31, 2025. Portions of such proxy statement are incorporated by reference into Part III of this Annual Report on Form 10-K.

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Summary of Product Revenue Allowance and Reserve Categories (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Fees And Patient Assistance [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 11,589	$ 5,674	$ 164
Provision related to sales in the current year	49,594	46,506	17,690
Adjustments related to prior period sales	298	1,461	(112)
Credits and payments made	(48,707)	(42,052)	(12,068)
Ending balance	12,774	11,589	5,674
Government, Other Rebates, and Chargebacks [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	31,533	8,898	1,936
Provision related to sales in the current year	140,065	89,094	26,661
Adjustments related to prior period sales	(13)	(19)	(1,223)
Credits and payments made	(128,658)	(66,440)	(18,476)
Ending balance	42,927	31,533	8,898
Returns [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	2,023	2,053	251
Provision related to sales in the current year	5,652	3,936	4,698
Adjustments related to prior period sales	(382)	(96)	(2,481)
Credits and payments made	(4,380)	(3,870)	(415)
Ending balance	2,913	2,023	2,053
Product Revenue Allowance and Reserves [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	45,145	16,625	2,351
Provision related to sales in the current year	195,311	139,536	49,050
Adjustments related to prior period sales	(97)	1,346	(3,817)
Credits and payments made	(181,745)	(112,362)	(30,960)
Ending balance	$ 58,614	$ 45,145	$ 16,625

Leases - Supplemental Cash Flow Information Related to Operating Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Leases [Abstract]
Operating cash flows from operating leases	$ 10,471	$ 9,263	$ 7,939
Operating lease assets obtained in exchange for lease obligations	$ 6,457		$ 2,700

Income Taxes - Components of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Current income tax expense:
U.S. State and Local	$ 1,550	$ 474	$ 1,869
Foreign	172	688	263
Total current income tax expense	1,722	1,162	2,132
Deferred income tax expense:
Total tax expense	$ 1,722	$ 1,162	$ 2,132

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Outstanding amount of sold accounts receivable	$ 0.0	$ 86.1
Accrued Expenses [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Product sales reserves	$ 58.6	$ 45.1

Income Taxes - Schedule of Reconciliation Between U.S. Federal Statutory Rate and Effective Tax rate (Detail)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Effective Income Tax Rate Reconciliation [Line Items]
US federal statutory income tax rate, Percentage of income before income taxes	21.00%	21.00%	21.00%
Research tax credits, Percent	23.70%	11.20%	2.20%
Nontaxable and nondeductible items
Stock-based compensation, Percent	45.40%	4.40%	5.10%
162M, Percent	6.80%	(1.40%)	(0.30%)
Other, Percent	2.50%	(0.20%)	0.30%
Cross-border tax laws
GILTI, Percent	2.60%	(30.30%)
Valuation allowance, Percent	23.90%	16.30%	(8.70%)
Prior year taxes, Percent		(2.50%)	(0.50%)
Domestic state and local income taxes, net of federal benefit, Percent	6.40%	(0.20%)	(0.40%)
Effective income tax provision, Percent	7.10%	(0.60%)	(0.40%)
Other Foreign Jurisdictions [Member]
Cross-border tax laws
Statutory income tax rate differential, Percent	1.00%	(0.20%)	(0.00%)
Bermuda [Member]
Cross-border tax laws
Statutory income tax rate differential, Percent	0.00%	(1.60%)	(0.00%)
Switzerland [Member]
Cross-border tax laws
Valuation allowance, Percent	(47.00%)	(5.80%)	(7.00%)
Statutory income tax rate differential, Percent	(81.80%)	(10.40%)	(11.80%)
Other, Percent	(1.60%)	(0.40%)	(0.00%)
Australia [Member]
Cross-border tax laws
Valuation allowance, Percent	6.20%	(0.70%)	(0.30%)
Statutory income tax rate differential, Percent	(1.80%)	0.30%	0.10%
Other, Percent	(0.20%)	(0.10%)	(0.10%)

Inventory

12 Months Ended

Dec. 31, 2025

Inventory Disclosure [Abstract]

Inventory

4. Inventory

The Company’s inventory of EMPAVELI and SYFOVRE consisted of the following as of December 31, 2025 and 2024 (in thousands):


	December 31,
	2025		2024
Raw materials	$	43,290	$	54,385
Semi-finished goods		121,207		92,872
Finished goods		13,018		9,860
Total inventories	$	177,515	$	157,117

The Company’s long-term inventory balance consists of raw materials and semi-finished goods that are not expected to be sold within the Company’s normal operating cycle.

Inventory amounts written down as a result of excess, obsolescence, unmarketability or other reasons are charged to cost of sales. For the years ended December 31, 2025 and 2024, the Company’s reserve for excess and obsolete inventory was $20.5 million and $19.0 million, respectively.

Equity Incentive Plans - Summary of Shares of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Feb. 29, 2020
Class Of Stock [Line Items]
Common stock reserved for future issuance	19,637,000	22,100,000	19,180,000
2017 Stock Incentive Plan [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	17,797,000	20,062,000	16,989,000
2017 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	209,000	411,000	553,000
2020 Inducement Stock Incentive Plan [Member]
Class Of Stock [Line Items]
Common stock reserved for future issuance	1,631,000	1,627,000	1,638,000	750,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Long-term Debt

12 Months Ended

Dec. 31, 2025

Debt Disclosure [Abstract]

Long-term Debt

7. Long-term Debt

Convertible Senior Notes

On September 16, 2019, the Company completed a private offering of convertible notes the 2019 Convertible Notes with an aggregate principal amount of $220.0 million issued pursuant to an indenture (the “Indenture”) with U.S. Bank National Association, as trustee.

The net proceeds from the sale of the 2019 Convertible Notes were approximately $212.9 million after deducting the initial purchasers’ discounts and commissions of $6.6 million and offering expenses of $0.5 million paid by the Company. The Company

used $28.4 million of the net proceeds from the sale of the 2019 Convertible Notes to pay the cost of the capped call transactions in September 2019, described below.

On May 12, 2020, the Company issued convertible notes (the “2020 Convertible Notes”) with an aggregate principal amount of $300.0 million. The net proceeds from the sale of the 2020 Convertible Notes were approximately $322.9 million after deducting the purchasers’ discounts and commission of $5.7 million and offering expenses of $0.3 million. The Company used $43.1 million of the net proceeds from the sale of the 2020 Convertible Notes to pay the cost of the additional capped call transactions in May 2020, described below.

The 2019 Convertible Notes and the 2020 Convertible Notes are referred to together as the “Convertible Notes”. The Convertible Notes are senior unsecured obligations of the Company and bear interest at a rate of 3.5% per year, payable semi-annually in arrears on March 15 and September 15 of each year, beginning on March 15, 2020. The Convertible Notes will mature on September 15, 2026, unless converted earlier, redeemed or repurchased in accordance with their terms.

The Convertible Notes are convertible into shares of the Company’s common stock at an initial conversion rate of 25.3405 shares per $1,000 principal amount of Convertible Notes (equivalent to an initial conversion price of approximately $39.4625 per share of common stock). The conversion rate is subject to customary anti-dilution adjustments. In addition, following certain events that occur prior to the maturity date or if the Company deliver a notice of redemption, the Company will increase the conversion rate for a holder who elects to convert its Convertible Notes in connection with such corporate event or a notice of redemption, as the case may be, in certain circumstances as provided in the Indenture.

Prior to March 15, 2026, the Convertible Notes are convertible only under the following circumstances:

•

during any calendar quarter, if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day;

•

during the five-business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of the Convertible Notes for each such trading day was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day;

•

if the Company calls any or all of the Convertible Notes for redemption, at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date; or

•

upon the occurrence of corporate events specified in the Indenture.

On or after March 15, 2026 until the close of business on the second scheduled trading day immediately preceding the maturity date of the Convertible Notes, holders may convert the Convertible Notes at any time. Upon conversion of the Convertible Notes, the Company will pay or deliver, as the case may be, cash, shares of the Company’s common stock or a combination of cash and shares of common stock, at the Company’s election.

During 2021 and 2022, holders of the 2019 Convertible Notes and the 2020 Convertible Notes converted approximately $425.4 million in aggregate principal amount into a total of 12,926,104 shares of the Company’s common stock. The Company accounted for these exchanges as induced conversions, resulting in the expensing of the fair value of shares issued in excess of the original terms of the Convertible Notes.

None of the circumstances outlined above were achieved during the years ended December 31, 2025 and 2024, and as such, the conditional conversion feature of the Convertible Notes was not triggered as of December 31, 2025 and 2024.

After September 20, 2023, the Company may redeem for cash all or a portion of the Convertible Notes, at its option, if the last
reported sale price of the Company’s common stock has been at least 130% of the conversion price then in effect for at least 20
trading days (whether or not consecutive), including the trading day immediately preceding the date on which the Company provides a
notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding
the date on which the Company provides notice of redemption. The redemption price will be equal to 100% of the principal amount of
the Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. If the Company calls
any Convertible Notes for redemption, it will constitute a “make-whole fundamental change” with respect to such Convertible Notes,
in which case the conversion rate applicable to the conversion of such Notes, if converted in connection with the redemption, will be
The Company has not called for redemption or redeemed any of the Convertible Notes as of
December 31, 2025.

If the Company undergoes a “fundamental change,” as defined in the Indenture, prior to maturity, subject to certain conditions,
holders may require the Company to repurchase for cash all or any portion of their Convertible Notes at a fundamental change

repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus any accrued and unpaid interest to, but
excluding, the fundamental change repurchase date.

As of December 31, 2025 and 2024, the Company held in treasury Convertible Notes in principal amount of $425.4 million which have not been cancelled.

As the Convertible Notes mature on September 15, 2026, the Company classified the Convertible Note as current liabilities as of December 31, 2025 and non-current liabilities as of December 31, 2024 on the Company’s consolidated balance sheets.

The outstanding balance of the Convertible Notes as of December 31, 2025 and 2024 consisted of the following (in thousands):


	December 31,
	2025			2024
Principal	$	93,897		$	93,897
Less: debt discount and issuance costs, net		(235	)		(556	)
Net carrying amount	$	93,662		$	93,341

The following table sets forth total interest expense recognized related to the Convertible Notes during the years ended December 31, 2025, 2024 and 2023 (in thousands):


	Year Ended December 31,
	2025		2024		2023
Amortization of debt issuance costs	$	321	$	309	$	297
Contractual interest expense		3,286		3,286		3,286
Total interest expense	$	3,607	$	3,595	$	3,583

Capped Call Transactions

On September 11, 2019 and May 6, 2020, concurrently with the pricings of the Convertible Notes, the Company entered into capped call transactions with two counterparties. The capped call transactions are expected generally to reduce the potential dilution to the Company’s common stock upon any conversion of Convertible Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted Convertible Notes, as the case may be, in the event that the market price per share of the Company’s common stock, as measured under the terms of the capped call transactions, is greater than the strike price of the capped call transactions, which is initially $39.4625 (the conversion price of the Convertible Notes) and is subject to anti-dilution adjustments substantially similar to those applicable to the conversion rate of such Convertible Notes. If, however, the market price per share of the Company’s common stock, as measured under the terms of the capped call transactions, exceeds the cap price of the capped call transactions, which is initially $63.14 per share, there would nevertheless be dilution and/or there would not be an offset of such potential cash payments, in each case, to the extent that such market price exceeds the cap price of the capped call transactions.

On February 27, 2024, the Company unwound a portion of the capped call transactions with the capped call counterparties, which resulted in cash proceeds to the Company of $98.8 million. The unwind transactions were settled at a volume-weighted average price per share of $64.11 on March 8, 2024.

As of December 31, 2025, the Company holds remaining capped call transactions in a notional amount corresponding to $93.9 million principal amount of Convertible Notes.

Financing Agreement and Credit Facility

On May 13, 2024, the Company and certain of its subsidiaries entered into a financing agreement (the “Sixth Street Financing Agreement”) with the lenders party thereto (the “Lenders”), and Sixth Street Lending Partners (“Sixth Street”), as the administrative agent and collateral agent for the Lenders.

The Sixth Street Financing Agreement provides for a senior secured term loan facility of up to $475.0 million (the “Credit Facility”), consisting of an initial draw of $375.0 million at closing and a potential additional $100.0 million draw at the Company’s option upon satisfaction of a $50.0 million minimum cash requirement and a requirement that the Company’s trailing three-month sales of SYFOVRE is at least $180.0 million prior to the $100.0 million draw by September 30, 2025. The Company did not draw down the additional $100.0 million and the option expired September 30, 2025.

The Credit Facility matures on May 13, 2030 (the “Maturity Date”) and bears interest at (i) in the case of SOFR Loans, an annual rate equal to 3-month Term SOFR (subject to 1.00% floor), plus (ii) 5.75%. Certain additional commitment and undrawn amount fees are also payable in connection with the Credit Facility.

The net proceeds from the initial draw of the Credit Facility were approximately $358.2 million, net of $16.8 million of issuance costs. The Company used $326.5 million of the proceeds from the initial draw of the Credit Facility to buy out its remaining obligations to SFJ Pharmaceuticals Group.

The Credit Facility does not provide for scheduled amortization payments during the term. All principal will be due on the Maturity Date. The Company will have the right to prepay loans under the Credit Facility at any time. The Company is required to repay loans under the Credit Facility with proceeds from certain asset sales, condemnation events and extraordinary receipts, subject, in some cases, to reinvestment rights. Repayments are subject to a prepayment premium. Repayments may be made after the first year of the loan and are subject to a prepayment premium up to 3%, depending on timing.

On July 1, 2025, the Lenders and Sixth Street consented to the Royalty Agreement as further described in Note 10 (the “Six Street Consent”). In connection with the Sixth Street Consent, the Company agreed to extend by one year from the effective date of the Consent the periods in which certain prepayment premiums would be owed under the Sixth Street Financing Agreement. This effectively extended the period the prepayment premium would be owed from one year after the date of the initial draw, or May 13, 2024, to one year after the effective date of the Sixth Street Consent, or July 1, 2025.

All obligations under the Sixth Street Financing Agreement are secured on a first-priority basis, subject to certain exceptions, by security interests in substantially all assets of the Company and certain subsidiaries of the Company, including its intellectual property, and are guaranteed by certain subsidiaries of the Company, including foreign subsidiaries, subject to certain exceptions.

The Sixth Street Financing Agreement contains customary covenants, including, without limitation, a financial covenant to maintain liquidity of at least $50.0 million if the Company’s market capitalization is below $3.0 billion, and negative covenants that, subject to certain exceptions, restrict indebtedness, liens, investments (including acquisitions), fundamental changes, asset sales and licensing transactions, dividends, modifications to material agreements, payment of subordinated indebtedness, and other matters customarily restricted in such agreements. Among other permissions, the Company is permitted, on terms and conditions set forth on the Sixth Street Financing Agreement, to enter into a separate asset-based financing arrangement with a third-party in an amount of up to $100.0 million, which amount is increased to $200.0 million upon certain sales or market capitalization thresholds, and to have outstanding convertible unsecured notes in an amount equal to the greater of $400.0 million and 10% of the Company’s market capitalization, but not to exceed $600.0 million. The Company is subject to restrictions on sales and licensing transactions with respect to its core intellectual property, defined to include SYFOVRE, EMPAVELI, and other pegcetacoplan product assets, subject to certain exceptions, including certain transactions related to areas outside the United States and Europe.

The outstanding balance of the Credit Facility as of December 31, 2025 and 2024 consisted of the following (in thousands):


	December 31,			December 31,
	2025			2024
Principal	$	375,000		$	375,000
Less: debt discount and issuance costs		(13,336	)		(15,511	)
Net carrying amount	$	361,664		$	359,489

The following table sets forth total interest expense recognized related to the Credit Facility as of December 31, 2025 and 2024 (in thousands):


	December 31,
	2025		2024
Amortization of debt issuance costs	$	2,175	$	1,250
Contractual interest expense		37,947		26,082
Total interest expense	$	40,122	$	27,332

No interest expense incurred for the year ended December 31, 2023 as the Credit Facility commenced in 2024.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Nature of Organization and Operations

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Organization and Operations

1. Nature of Organization and Operations

Apellis Pharmaceuticals, Inc. (the “Company”) is a commercial-stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutic compounds to treat diseases with high unmet needs through the inhibition of the complement system, which is an integral component of the immune system, at the level of C3, the central protein in the complement cascade.

The Company was incorporated in September 2009 under the laws of the State of Delaware. The Company’s principal executive offices are located in Waltham, Massachusetts.

The Company’s operations since inception have included organizing and staffing the Company, acquiring rights to product candidates, business planning, raising capital, developing its product candidates, commercializing EMPAVELI (pegcetacoplan) for the treatment of paroxysmal nocturnal hemoglobinuria (“PNH”), C3 glomerulopathy (“C3G”) and primary immune complex membranoproliferative glomerulonephritis (“primary IC-MPGN”), and commercializing SYFOVRE (pegcetacoplan injection) for the treatment of geographic atrophy secondary to age-related macular degeneration (“GA”).

The Company is subject to risks common in the biotechnology industry including, but not limited to, raising additional capital, development by its competitors of new technological innovations, its ability to successfully complete preclinical and clinical development of product candidates and receive timely regulatory approval of products, market acceptance of the Company’s products, protection of proprietary technology, healthcare cost containment initiatives, and compliance with governmental regulations, including those of the U.S. Food and Drug Administration (“FDA”).

Follow-on Public Offerings

On February 22, 2023, the Company issued and sold 4,007,936 shares of common stock and, in lieu of common stock to investors who so chose, pre-funded warrants to purchase 2,380,956 shares of common stock in a follow-on offering, including 833,333 shares sold pursuant to the underwriters’ exercise in full of their option to purchase additional shares of common stock. The price to the public of the shares of common stock was $63.00 per share and the price to the public of the pre-funded warrants was $62.9999 per pre-funded warrant. The pre-funded warrants have an exercise price equal to $0.0001 per share and do not expire. The pre-funded warrants were accounted for as equity instruments. The Company received total net proceeds of $384.4 million, after deducting underwriting discounts and commissions of $18.8 million and offering costs of $0.3 million. For the period ended December 31 2024, 2,299,991 shares of common stock were issued from the exercise of pre-funded warrants. As of December 31, 2025, pre-funded warrants to purchase 80,956 shares of the Company's common stock were still outstanding.

Liquidity and Going Concern

The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. From inception to December 31, 2025, the Company has incurred cash outflows from operations, losses from operations, and had an accumulated deficit of $3.0 billion, primarily as a result of expenses incurred through a combination of research and development activities related to the Company’s various product candidates and expenses incurred in connection with product launches and commercialization costs.

The Company believes that its cash and cash equivalents of $466.2 million at December 31, 2025 combined with cash anticipated to be generated from sales of EMPAVELI and from SYFOVRE will be sufficient to fund its operations and capital expenditure requirements for at least twelve months from the date of issuance of these consolidated financial statements.

Equity Incentive Plans

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Equity Incentive Plans

14. Equity Incentive Plans

Share-based Compensation

The Company’s Board of Directors adopted, and its stockholders approved, an equity incentive plan in 2010 (as amended, the “2010 Plan”). The Board of Directors and stockholders amended the 2010 Plan in August 2017 to increase the number of shares of common stock reserved for issuance thereunder to 6,188,466. The 2010 Plan allowed for the grant of incentive stock options and non-qualified stock options to purchase common stock for employees, directors and consultants under terms and conditions established by the Board of Directors. Incentive stock options and nonqualified stock options were granted at exercise prices that were no less than 100% of the estimated fair value per share of the common stock on the date of grant. If an individual owns capital stock representing more than 10% of the voting shares, the price of each share was at least 110% of the fair value on the date of grant. The Board of Directors determined the fair value of common stock with the assistance of a third-party specialist. Options expire 10 years from the issuance date. Following the adoption of Company’s the 2017 Stock Incentive Plan (the “2017 Plan”), the Company no longer grants stock options or other awards under the 2010 Plan.

In October 2017, the Company’s Board of Directors adopted, and its stockholders approved, the 2017 Plan, which became effective on November 8, 2017. The 2017 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, awards of restricted stock, restricted stock units and other stock-based awards. The number of shares of common stock reserved for issuance under the 2017 plan is the sum of (i) 1,359,587 shares of common stock, plus (ii) an additional number of shares of common stock equal to the sum of (a) the number of shares of common stock reserved for issuance under the 2010 equity incentive plan that remained available for future issuance immediately prior to the effectiveness of the 2017 Plan, which was 299,568 shares, and (b) the number of shares of common stock subject to outstanding awards under the 2010 equity incentive plan upon effectiveness of the 2017 plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by us at their original issuance price pursuant to a contractual repurchase right plus (iii) an annual increase, to be added the first day of each fiscal year, beginning with the fiscal year ending December 31, 2018 and continuing until, and including, the fiscal year ending December 31, 2027, equal to the lowest of (i) 4,219,409 shares of common stock, (ii) 4.0% of the number of shares of common stock outstanding on the first day of the fiscal year and (iii) an amount determined by the board of directors. On January 1, 2025, the shares available for future issuance under the 2017 plan were increased by 4,219,409 shares pursuant to the annual increase described above. As of December 31, 2025, there were 2,865,381 shares available for future grants under the 2017 Plan. In January 2026, the shares available for future issuance under the 2017 plan were increased by an additional 4,219,409 shares.

Additionally, since 2019, the Company has granted equity awards as equity inducement awards material to entry into employment with the Company to certain newly hired employees outside of the Company’s existing plans in accordance with Nasdaq listing rule 5635(c)(4). In February 2020, the Board of Directors adopted the 2020 Inducement Stock Incentive Plan (the “2020 Plan”), which permitted the Company to grant equity awards to newly hired employees in accordance with Nasdaq listing rule 5635(c)(4).

The aggregate number of shares reserved for issuance under the 2020 Plan was initially 750,000 shares. The Board of Directors amended the 2020 Plan to add 200,000 shares on January 1, 2024, which increased the total number of shares reserved for issuance to 1,950,000 shares as of January 1, 2024. As of December 31, 2025, there were 1,032,021 shares available for future grants under the 2020 Plan. No additional shares have been reserved under the 2020 Plan in 2025 or 2026.

In October 2017, the Company’s board of directors adopted, and the Company’s stockholders approved the 2017 Employee Stock Purchase Plan (“ESPP”) and provides participating employees with the opportunity to purchase up to an aggregate of 468,823 shares of common stock. The number of shares of common stock reserved for issuance under the 2017 ESPP will automatically increase on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2018 and continuing until, and including, the fiscal year ending December 31, 2027, equal to the lowest of (i) 937,646 shares of common stock, (ii) 1.0% of the number of shares of common stock outstanding on the first day of the fiscal year and (iii) an amount determined by the board of directors. The board of directors initiated the first offering under ESPP in October 2019. On December 31, 2025, 208,848 shares of common stock remained available for issuance pursuant to the ESPP. On January 1, 2026, the shares available for future issuance under the ESPP were increased by 500,000 shares pursuant to the annual increase described above.

The Company has reserved the following shares of common stock for future issuance (in thousands):


	December 31,
	2025		2024		2023
Shares reserved under 2017 Equity Incentive Plan		17,797		20,062		16,989
Shares reserved under 2017 Employee Stock Purchase Plan		209		411		553
Shares reserved under 2020 Inducement Stock Incentive Plan		1,631		1,627		1,638
Total		19,637		22,100		19,180

Total share-based compensation expense related to the various plans during the years ended was as follows (in thousands):


	Year Ended December 31,
	2025		2024		2023
Research and development	$	40,105	$	41,267	$	45,644
Selling, general and administrative		63,898		72,861		60,301
Total share-based compensation expense included in expenses	$	104,003	$	114,128	$	105,945
Capitalized share-based compensation expense to inventory (1)		5,128		—		—
Total share-based compensation	$	109,131	$	114,128	$	105,945

(1) Prior to the year ended December 31, 2025, capitalized share-based compensation expenses into inventory were not material.

Stock Options—Options granted to employees typically vest over 48 months in installments of (i) 25% at the one-year anniversary and (ii) in either 36 equal monthly or 12 equal quarterly installments beginning in the thirteenth month after the initial vesting commencement date (as defined) subject to the employee’s continuous service with the Company.

Under the Executive Separation Benefits and Retention Plan and by resolutions adopted by the Compensation Committee in October 2019, the stock options granted to the Company’s executives and employees will become fully vested upon the occurrence of a change in control, as defined in the Executive Separation Benefits and Retention Plan, if such executive or senior employee is terminated without cause or resigns for good reason within 12 months after such change in control.

The following table summarizes the Company’s stock option activity:


				Weighted -		Weighted -
				Average		Average		Aggregate
				Exercise		Contractual		Intrinsic
	Shares			Price		Life		Value
	(in thousands)			Per Share		(in years)		(in thousands)
Outstanding, December 31, 2024		8,048		$	35.36
Granted		2,919			20.17
Exercised		(438	)		12.65
Forfeited		(1,466	)		44.07
Outstanding, December 31, 2025		9,063		$	30.16
Options exercisable, December 31, 2025		5,919		$	33.00		4.09	$	24,018
Expected to vest, December 31, 2025		3,144		$	24.82		3.89	$	14,763

The aggregate intrinsic values were calculated as the difference between the exercise price of the options and the fair value of the common stock.

During the years ended December 31, 2025, 2024 and 2023, the Company granted stock options to purchase an aggregate of 2.9 million, 0.7 million and 0.8 million shares of its common stock, respectively with weighted average grant date fair values per share of $9.66, $42.61 and $34.26, respectively.

The aggregate intrinsic value of options exercised during the years ended December 31, 2025, 2024 and 2023 were $3.0 million, $46.0 million, and $181.0 million, respectively, calculated as the difference between the exercise price of the options and the fair value of the common stock on the respective date of exercise.

As of December 31, 2025, unrecognized compensation expense related to unvested options was $32.3 million, which the Company expects to recognize over an estimated weighted-average period of 1.9 years.

The assumptions used in the Black-Scholes model to estimate the grant date fair value are as follows:


	Year Ended December 31,
	2025	2024	2023
Risk-free interest rate	3.77% - 4.42%	3.94 - 4.36%	3.50 - 4.01%
Dividend yield	0%	0%	0%
Volatility	70.32% - 73.11%	71.91 - 77.01%	68.4 - 71.0%
Expected terms (years)	2.25 - 6.25	3.81 - 6.08	3.81 - 6.08

Restricted Stock Units— The fair value of RSUs is estimated based upon the closing market price of the Company’s common stock on the date of grant. RSUs generally vest annually over a four-year period.

The following table summarizes the Company’s RSU activity:


	Number of Stock Units (in thousands)			Weighted Average Grant Date Fair Value Per Share
Unvested Balance at December 31, 2024		3,961		$	53.19
Granted		3,343			27.41
Vested		(1,487	)		50.18
Forfeited		(1,084	)		45.05
Unvested Balance at December 31, 2025		4,733		$	37.69

The fair value of restricted stock units vested during the year ended December 31, 2025, 2024 and 2023, respectively, were $74.6 million, $65.5 million and $42.2 million.

As of December 31, 2025, there was approximately $118.2 million of related unrecognized compensation cost which the Company expects to recognize over a remaining weighted average period of 2.5 years.

Performance and Market-Based Stock Unit Awards

Market-Based RSUs

In January 2025, the Company granted 646,488 shares of performance restricted stock units (“PSUs”) to each of its executives pursuant to the 2017 Plan. Each performance restricted stock unit represents a contingent right to receive one share of the Company’s common stock. The PSUs will vest, subject to the satisfaction of the market conditions outlined below, so long as the grantee has a continuing service relationship with the Company. All vesting is dependent on grantee remaining employed by the Company on the applicable vesting dates. The market condition shall mean the attainment of Company relative total shareholder return (“rTSR”) performance compared to the Nasdaq Biotechnology Index (“NBI”) during the following three performance periods: 2025, 2025 - 2026, and 2025 - 2027, as determined by the Compensation Committee of the board of directors, utilizing a twenty (20) business day average stock price preceding the commencement date and preceding the conclusion of the performance period, with the following potential target threshold payout:

• 25th percentile relative TSR = 50% of original number of rTSR PSUs

• 55th percentile relative TSR = 100% of the original number of rTSR PSUs

• 90th percentile or greater relative TSR = 200% of the original number of rTSR PSUs

The Company used a Monte Carlo model to estimate the grant-date fair value of the rTSR PSUs. Share-based compensation expense for the rTSR PSUs is recorded in the consolidated statement of operations and comprehensive income/(loss) over the service period regardless of whether the market condition is achieved. Assumptions and estimates utilized in the calculation of the fair value of the rTSR PSUs include the risk-free interest rate, dividend yield, expected volatility based on the historical volatility of the Company and the performance period of the award.

The table below sets forth the weighted average grant date fair value assumptions used to value the rTSR PSUs:


	Year Ended December 31,
	2025
Risk-free interest rate	4.50%
Dividend yield	0%
Volatility	72.20%

The following table summarizes the Company’s rTSR PSU activity:


	Number of Stock Units (in thousands)			Weighted Average Grant Date Fair Value Per Share
Unvested Balance at December 31, 2024		—		$	—
Granted		646			44.04
Vested		—			—
Forfeited		(99	)		44.04
Unvested Balance at December 31, 2025		547		$	44.04

As of December 31, 2025, there was approximately $10.7 million of related unrecognized compensation cost which the Company expects to recognize over a remaining weighted average period of 1.6 years.

Performance-Based RSUs

In June 2025, the Company granted 1,238,937 performance-based RSUs to all active employees pursuant to the 2017 Plan. Each performance-based restricted stock unit represents a contingent right to receive one share of the Company’s common stock. The performance-based RSUs will vest, subject to the satisfaction of certain regulatory and revenue performance conditions, so long as the grantee has a continuing service relationship. The fair value of the performance-based RSUs is estimated based upon the closing market price of the Company’s common stock on the date of grant. Of the 1,238,937 performance-based RSUs legally granted, the Company notes a grant date per ASC Topic 718, Compensation – stock compensation (“ASC 718”) was only established for 743,265 awards as certain criteria to establish a grant date under ASC 718 was not met for 495,672 awards.

During the year ended December 31, 2025, no expense was recognized because the performance conditions were not considered probable of achievement.

The following table summarizes the Company’s performance-based RSU activity:


	Number of Stock Units (in thousands)			Weighted Average Grant Date Fair Value Per Share
Unvested Balance at December 31, 2024		—		$	—
Granted		743			19.39
Vested		—			—
Forfeited		(31	)		19.39
Unvested Balance at December 31, 2025		712		$	19.39

Employee Stock Purchase Plan— Eligible employees who elect to participate in an offering under the ESPP may have up to 15% of their earnings withheld, subject to certain limitations, to purchase shares of common stock pursuant to the ESPP. The price of common stock purchased under the ESPP is equal to 85% of the lower of the fair market value of the common stock at the commencement date of each offering period or the relevant purchase date. During the year ended December 31, 2025, a total of 202,092 shares of common stock were issued under the ESPP at an average per share price of $16.58. During the year ended

December 31, 2025, the Company recorded cash received from the issuance of stock to the ESPP of $3.4 million and recorded $1.4 million of share-based compensation expense related to the ESPP.

Long-term Debt - Summary of Credit Facility (Detail) - Credit Facility [Member] - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Principal	$ 375,000	$ 375,000
Less: debt discount and issuance costs	(13,336)	(15,511)
Net carrying amount	$ 361,664	$ 359,489

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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-Paragraph 1
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+ Details

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2025 USD ($) Segment	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Number of operating segment \| Segment	1
Advertising costs	$ 91,800,000	$ 83,300,000	$ 86,500,000
Allowance for credit losses	0	0
Allowance for credit losses, writeoff	$ 0	$ 0
Accounting standards update [extensible enumeration]	ASU 2023-09
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Dec. 31, 2025
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true
Maximum [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Sale of outstanding accounts receivables	$ 100,000,000

Employee Retirement Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Tax Status [Extensible Enumeration]	us-gaap:QualifiedPlanMember	us-gaap:QualifiedPlanMember	us-gaap:QualifiedPlanMember
Minimum age of full-time employees eligible to participate in the plan	21 years
Employer contributions made to the 401(k) Plan	$ 5.7	$ 5.1	$ 5.7
Swiss Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Underfunded status	0.2	1.6
Fair value of plan assets	11.3	16.7
Projected benefit obligation	11.5	18.3
Accumulated benefit obligation	0.1	0.6
Net periodic benefit cost	$ 0.7	$ 1.2

Consolidated Statements of Changes in Stockholder's Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2022	$ 169,872	$ 11	$ 2,479,596	$ (875)	$ (2,308,860)
Beginning balance, Shares at Dec. 31, 2022		110,772,000
Issuance of common stock and pre-funded warrants in common stock offering	384,387	$ 1	384,386
Issuance of common stock and pre-funded warrants in common stock offering, shares		4,008,000
Issuance of common stock upon exercise of stock options	71,274		71,274
Issuance of common stock upon exercise of stock options, shares		3,858,000
Vesting of restricted stock units	(11,040)		(11,040)
Vesting of restricted stock units, shares		806,000
Share-based compensation expense	105,945		105,945
Issuance of common stock to employee stock purchase plan	5,378		5,378
Issuance of common stock to employee stock purchase plan, shares		112,000
Unrealized gain (loss) on pension benefit plan	(2,618)			(2,618)
Net income (loss)	(528,628)				(528,628)
Foreign currency translation	(49)			(49)
Ending balance at Dec. 31, 2023	194,521	$ 12	3,035,539	(3,542)	(2,837,488)
Ending balance, Shares at Dec. 31, 2023		119,556,000
Exercise of pre-funded warrants, shares		2,300,000
Proceeds from settlement of capped call	98,763		98,763
Issuance of common stock upon exercise of stock options	14,316		14,316
Issuance of common stock upon exercise of stock options, shares		1,080,000
Vesting of restricted stock units	(57)		(57)
Vesting of restricted stock units, shares		1,417,000
Share-based compensation expense	114,128		114,128
Issuance of common stock to employee stock purchase plan	4,512		4,512
Issuance of common stock to employee stock purchase plan, shares		142,000
Unrealized gain (loss) on pension benefit plan	591			591
Net income (loss)	(197,878)				(197,878)
Foreign currency translation	(357)			(357)
Ending balance at Dec. 31, 2024	228,539	$ 12	3,267,201	(3,308)	(3,035,366)
Ending balance, Shares at Dec. 31, 2024		124,495,000
Issuance of common stock and pre-funded warrants in common stock offering, shares		80,956
Issuance of common stock upon exercise of stock options	$ 5,545		5,545
Issuance of common stock upon exercise of stock options, shares	438,000	438,000
Vesting of restricted stock units	$ (11)		(11)
Vesting of restricted stock units, shares		1,486,000
Share-based compensation expense	109,131		109,131
Issuance of common stock to employee stock purchase plan	3,350		3,350
Issuance of common stock to employee stock purchase plan, shares		202,000
Unrealized gain (loss) on pension benefit plan	107			107
Net income (loss)	22,388				22,388
Foreign currency translation	1,098			1,098
Ending balance at Dec. 31, 2025	$ 370,147	$ 12	$ 3,385,216	$ (2,103)	$ (3,012,978)
Ending balance, Shares at Dec. 31, 2025		126,621,000

Leases (Tables)

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Schedule of Additional Information Related to Operating Lease

Additional information related to the operating leases is as follows (in thousands):


	December 31,
	2025			2024
Right-of-use assets	$	18,195		$	16,083
Operating lease liabilities	$	19,034		$	16,954
Weighted average remaining term in years		3.31			2.73
Weighted average discount rate used to measure outstanding lease liabilities		6.52	%		6.20	%

Supplemental Cash Flow Information Related to Operating Leases

Supplemental cash flow information related to operating leases for the years ended December 31, 2025, 2024 and 2023 is as follows (in thousands):


	2025		2024		2023
Operating cash flows from operating leases	$	10,471	$	9,263	$	7,939
Operating lease assets obtained in exchange for lease obligations	$	6,457	$	—	$	2,700

Maturity of Operating Lease Liabilities

The maturity of the Company’s operating lease liabilities as of December 31, 2025 are as follows (in thousands):


2026	$	7,940
2027		5,808
2028		3,581
2029		3,324
2030 and thereafter		373
Total future minimum lease payments		21,026
Less imputed interest		(1,992	)
Total operating lease liabilities	$	19,034

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Disaggregation of Product Revenue by Major Source (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	$ 1,003,782	$ 781,367	$ 396,591
EMPAVELI [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	102,449	98,091	91,033
SYFOVRE [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	586,934	611,863	275,248
Product revenue, net [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	$ 689,383	$ 709,954	$ 366,281

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Equity Incentive Plans - Schedule of Unvested Restricted Stock Units Activity (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2025 $ / shares shares
Restricted Stock Units [Member]
Number of Stock Units
Unvested Beginning Balance \| shares	3,961
Granted \| shares	3,343
Vested \| shares	(1,487)
Forfeited \| shares	(1,084)
Unvested Ending Balance \| shares	4,733
Weighted Average Grant Date Fair Value Per Share
Unvested Beginning Balance \| $ / shares	$ 53.19
Granted \| $ / shares	27.41
Vested \| $ / shares	50.18
Forfeited \| $ / shares	45.05
Unvested Ending Balance \| $ / shares	$ 37.69
Market-Based RSUs [Member]
Number of Stock Units
Unvested Beginning Balance \| shares	0
Granted \| shares	646
Vested \| shares	0
Forfeited \| shares	(99)
Unvested Ending Balance \| shares	547
Weighted Average Grant Date Fair Value Per Share
Unvested Beginning Balance \| $ / shares	$ 0
Granted \| $ / shares	44.04
Vested \| $ / shares	0
Forfeited \| $ / shares	44.04
Unvested Ending Balance \| $ / shares	$ 44.04
Performance-Based RSUs [Member]
Number of Stock Units
Unvested Beginning Balance \| shares	0
Granted \| shares	743
Vested \| shares	0
Forfeited \| shares	(31)
Unvested Ending Balance \| shares	712
Weighted Average Grant Date Fair Value Per Share
Unvested Beginning Balance \| $ / shares	$ 0
Granted \| $ / shares	19.39
Vested \| $ / shares	0
Forfeited \| $ / shares	19.39
Unvested Ending Balance \| $ / shares	$ 19.39

Prepaid and Other Current Assets - Summary of Prepaid Assets and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Prepaid Expense and Other Assets, Current [Abstract]
Down payments for inventory	$ 2,201	$ 1,080
Prepaid research and development	22,096	7,780
Other prepaid assets	9,515	9,508
Royalties receivable	496	4,525
Receivable from collaboration agreement	2,442	2,272
Deposits and other current assets	1,553	4,847
Total prepaid and other current assets	$ 38,303	$ 30,012

Equity Incentive Plans - Additional Information (Detail)			1 Months Ended				12 Months Ended
	Jan. 01, 2026 shares	Jan. 01, 2024 shares	Jun. 30, 2025 shares	Jan. 31, 2025 shares	Oct. 31, 2017 shares	Aug. 31, 2017 shares	Dec. 31, 2025 USD ($) Days $ / shares shares	Dec. 31, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Jan. 01, 2025 shares	Feb. 29, 2020 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable increased during the period		200,000
Common stock reserved for future issuance							19,637,000	22,100,000	19,180,000
Stock options vesting period							48 months
Stock options vesting description							Options granted to employees typically vest over 48 months in installments of (i) 25% at the one-year anniversary and (ii) in either 36 equal monthly or 12 equal quarterly installments beginning in the thirteenth month after the initial vesting commencement date (as defined) subject to the employee’s continuous service with the Company.
Aggregate number of stock options granted to purchase common stock							2,919,000	700,000	800,000
Weighted - Average Grant Date Fair Value Per Option, Granted \| $ / shares							$ 9.66	$ 42.61	$ 34.26
Aggregate intrinsic value of options exercised in period \| $							$ 3,000,000	$ 46,000,000	$ 181,000,000
Unrecognized compensation expense \| $							$ 32,300,000
Estimated weighted-average period to recognize							1 year 10 months 24 days
Common stock, par value \| $ / shares							$ 0.0001	$ 0.0001
Common stock, issued							126,621,000	124,495,000
Common stock issued at average per share price \| $ / shares							$ 12.65
Total share-based compensation expense included in expenses \| $							$ 104,003,000	$ 114,128,000	105,945,000
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting period							4 years
Fair market value of restricted stock units vested \| $							$ 74,600,000	$ 65,500,000	$ 42,200,000
Unrecognized compensation expense \| $							$ 118,200,000
Estimated weighted-average period to recognize							2 years 6 months
Shares granted							3,343,000
Market-Based RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense \| $							$ 10,700,000
Estimated weighted-average period to recognize							1 year 7 months 6 days
Shares granted							646,000
Performance-Based RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted							743,000
Total share-based compensation expense included in expenses \| $							$ 0
Equity Incentive Plan 2010 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for issuance						6,188,466
Percentage of voting shares						10.00%
Options expire from issuance date						10 years
Equity Incentive Plan 2010 [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of estimated fair value per share of common stock on the date of grant						100.00%
Equity Incentive Plan 2010 [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage price of each share of the fair value on date of grant						110.00%
2017 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for issuance					1,359,587
Percentage of voting shares					4.00%
Number of shares available for future grant					299,568		2,865,381			4,219,409
Shares issuable increased during the period					4,219,409
Common stock issuance description							equal to the lowest of (i) 4,219,409 shares of common stock, (ii) 4.0% of the number of shares of common stock outstanding on the first day of the fiscal year and (iii) an amount determined by the board of directors.
Common stock reserved for future issuance							17,797,000	20,062,000	16,989,000
2017 Stock Incentive Plan [Member] \| Market-Based RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted				646,488
Number of business days utilized for average stock price of performance period \| Days							20
2017 Stock Incentive Plan [Member] \| Potential Target Threshold Payout of 25th Percentile [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares to be issued on achievement of total shareholder return percentile							50.00%
2017 Stock Incentive Plan [Member] \| Potential Target Threshold Payout of 55th Percentile [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares to be issued on achievement of total shareholder return percentile							100.00%
2017 Stock Incentive Plan [Member] \| Potential Target Threshold Payout of 90th Percentile [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares to be issued on achievement of total shareholder return percentile							200.00%
2017 Stock Incentive Plan [Member] \| Performance-Based RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted			1,238,937
2017 Stock Incentive Plan [Member] \| Awards Granted as per ASC 718 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted			743,265
2017 Stock Incentive Plan [Member] \| Awards Grant Date Criteria Not Met as per ASU 718 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted			495,672
2017 Stock Incentive Plan [Member] \| Subsequent Event [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	4,219,409
2020 Inducement Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		1,950,000					1,032,021			0
Common stock reserved for future issuance							1,631,000	1,627,000	1,638,000		750,000
2020 Inducement Stock Incentive Plan [Member] \| Subsequent Event [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant	0
2017 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for issuance					468,823
Percentage of voting shares							1.00%
2017 Employee Stock Purchase Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance							937,646
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage price of each share of the fair value on date of grant							85.00%
Number of shares available for future grant							208,848
Percentage of earnings withheld to purchase shares of common stock							15.00%
Common stock, issued							202,092
Common stock issued at average per share price \| $ / shares							$ 16.58
Cash received from issuance of purchase rights \| $							$ 3,400,000
Total share-based compensation expense included in expenses \| $							$ 1,400,000
Employee Stock Purchase Plan [Member] \| Subsequent Event [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable increased during the period	500,000

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ 22,388	$ (197,878)	$ (528,628)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Long-term Debt - Financing Agreement and Credit Facility - Additional Information (Details) - USD ($)		1 Months Ended	12 Months Ended
	May 13, 2024	May 31, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Proceeds from credit facility				$ 365,454,000
SYFOVRE [Member]
Debt Instrument [Line Items]
Minimum required sales to draw additional loan under credit facility	$ 180,000,000
Sixth Street Financing Agreement [Member]
Debt Instrument [Line Items]
Proceeds from initial draw amount under credit facility	358,200,000
Proceeds from net of isuance cost	16,800,000
Proceeds from credit facility	326,500,000	$ 326,500,000
Senior Secured Credit Facility [Member] \| Asset-Based Financing Arrangement [Member]
Debt Instrument [Line Items]
Available additional draw amount upon satisfaction of cash requirements	100,000,000
Senior Secured Credit Facility [Member] \| Sixth Street Financing Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	475,000,000
Available initial draw amount under credit facility	375,000,000
Available additional draw amount upon satisfaction of cash requirements	100,000,000		$ 0
Minimum cash requirements to draw additional loan under credit facility	50,000,000
Minimum required sales to draw additional loan under credit facility	$ 100,000,000
Credit facility maturity date	May 13, 2030
Variable interest rate percentage on base rate	1.00%
Debt instrument, variable interest rate, type [extensible enumeration]	SOFR [Member]
Debt instrument, covenant description			The Sixth Street Financing Agreement contains customary covenants, including, without limitation, a financial covenant to maintain liquidity of at least $50.0 million if the Company’s market capitalization is below $3.0 billion, and negative covenants that, subject to certain exceptions, restrict indebtedness, liens, investments (including acquisitions), fundamental changes, asset sales and licensing transactions, dividends, modifications to material agreements, payment of subordinated indebtedness, and other matters customarily restricted in such agreements. Among other permissions, the Company is permitted, on terms and conditions set forth on the Sixth Street Financing Agreement, to enter into a separate asset-based financing arrangement with a third-party in an amount of up to $100.0 million, which amount is increased to $200.0 million upon certain sales or market capitalization thresholds, and to have outstanding convertible unsecured notes in an amount equal to the greater of $400.0 million and 10% of the Company’s market capitalization, but not to exceed $600.0 million. The Company is subject to restrictions on sales and licensing transactions with respect to its core intellectual property, defined to include SYFOVRE, EMPAVELI, and other pegcetacoplan product assets, subject to certain exceptions, including certain transactions related to areas outside the United States and Europe.
Minimum required financial covenant if capitalization below three billion	$ 50,000,000
Market capitalization threshold percentage for credit facility	10.00%
Credit facility expiration date	Sep. 30, 2025
Senior Secured Credit Facility [Member] \| Sixth Street Financing Agreement [Member] \| Asset-Based Financing Arrangement [Member]
Debt Instrument [Line Items]
Revised Additional Available Draw Amount Upon Satisfaction of Sales or Market capitalization	$ 200,000,000
Minimum required convertible unsecured notes for additional loan amount	400,000,000
Market capitalization threshold for credit facility	$ 600,000,000
Credit Facility [Member]
Debt Instrument [Line Items]
Interest expense			$ 40,122,000	$ 27,332,000	$ 0
Credit Facility [Member] \| Sixth Street Financing Agreement [Member]
Debt Instrument [Line Items]
Debt instrument effective interest rate	5.75%
Credit Facility [Member] \| Maximum [Member] \| Sixth Street Financing Agreement [Member]
Debt Instrument [Line Items]
Percentage of prepayment premium	3.00%

Fair Value Measurements

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Fair Value Measurements

9. Fair Value Measurements

The following table presents the fair value of the Company’s financial instruments that are measured at fair value on a recurring basis as of December 31, 2025 and 2024 (in thousands):


		December 31, 2025
Balance Sheet Classification:	Type of Instrument	Level 1		Level 2		Level 3		Total
Financial Assets:
Cash and cash equivalents:	Money market funds	$	349,615	$	—	$	—	$	349,615
Total Financial Assets		$	349,615	$	—	$	—	$	349,615

		December 31, 2024
Balance Sheet Classification:	Type of Instrument	Level 1		Level 2		Level 3		Total
Financial Assets:
Cash and cash equivalents:	Money market funds	$	276,868	$	—	$	—	$	276,868
Total Financial Assets		$	276,868	$	—	$	—	$	276,868

The Convertible Notes are financial instruments that are reported in the consolidated financial statements at historical cost. The Convertible Notes are Level 1 within the fair value level hierarchy as of December 31, 2025 and 2024. The fair value of the Convertible Notes was $97.5 million as of December 31, 2025 and $102.3 million as of December 31, 2024. The Convertible Notes accrue a semi-annual coupon at an annual rate of 3.5%, which was included in accrued expenses in the consolidated balance sheets as of December 31, 2025 and 2024.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
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-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Consolidated Statements of Operations and Comprehensive Income/(Loss) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenue:
Revenue	$ 1,003,782	$ 781,367	$ 396,591
Operating expenses:
Cost of sales	102,236	117,723	58,510
Research and development	295,854	327,570	354,387
Selling, general and administrative	550,265	501,053	500,815
Total operating expenses:	948,355	946,346	913,712
Net operating income/(loss)	55,427	(164,979)	(517,121)
Loss on extinguishment of development liability		(1,949)
Interest income	13,143	12,773	20,933
Interest expense	(44,327)	(40,391)	(29,581)
Other expense, net	(133)	(2,170)	(727)
Net income/(loss) before taxes	24,110	(196,716)	(526,496)
Income tax expense	1,722	1,162	2,132
Net income/(loss)	22,388	(197,878)	(528,628)
Other comprehensive income/(loss):
Unrealized gain/(loss) on pension plans	107	591	(2,618)
Foreign currency translation	1,098	(357)	(49)
Total other comprehensive income/(loss)	1,205	234	(2,667)
Comprehensive income/(loss), net of tax	$ 23,593	$ (197,644)	$ (531,295)
Net income/(loss) per common share - basic	$ 0.18	$ (1.6)	$ (4.45)
Net income/(loss) per common share - diluted	$ 0.2	$ (1.6)	$ (4.45)
Weighted-average number of common shares used in net income/(loss) per common share - basic	126,145	123,905	118,678
Weighted-average number of common shares used in net income/(loss) per common share - diluted	129,855	123,905	118,678
Product revenue, net [Member]
Revenue:
Revenue	$ 689,383	$ 709,954	$ 366,281
Licensing and other revenue [Member]
Revenue:
Revenue	$ 314,399	$ 71,413	$ 30,310

Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2025

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Summary of Shares of Common Stock Reserved for Future Issuance

The Company has reserved the following shares of common stock for future issuance (in thousands):


	December 31,
	2025		2024		2023
Shares reserved under 2017 Equity Incentive Plan		17,797		20,062		16,989
Shares reserved under 2017 Employee Stock Purchase Plan		209		411		553
Shares reserved under 2020 Inducement Stock Incentive Plan		1,631		1,627		1,638
Total		19,637		22,100		19,180

Summary of Share-based Compensation Expense

Total share-based compensation expense related to the various plans during the years ended was as follows (in thousands):


	Year Ended December 31,
	2025		2024		2023
Research and development	$	40,105	$	41,267	$	45,644
Selling, general and administrative		63,898		72,861		60,301
Total share-based compensation expense included in expenses	$	104,003	$	114,128	$	105,945
Capitalized share-based compensation expense to inventory (1)		5,128		—		—
Total share-based compensation	$	109,131	$	114,128	$	105,945

(1) Prior to the year ended December 31, 2025, capitalized share-based compensation expenses into inventory were not material.

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity:


				Weighted -		Weighted -
				Average		Average		Aggregate
				Exercise		Contractual		Intrinsic
	Shares			Price		Life		Value
	(in thousands)			Per Share		(in years)		(in thousands)
Outstanding, December 31, 2024		8,048		$	35.36
Granted		2,919			20.17
Exercised		(438	)		12.65
Forfeited		(1,466	)		44.07
Outstanding, December 31, 2025		9,063		$	30.16
Options exercisable, December 31, 2025		5,919		$	33.00		4.09	$	24,018
Expected to vest, December 31, 2025		3,144		$	24.82		3.89	$	14,763

Summary of Assumption Used to Estimate Grant Date Fair Value

The assumptions used in the Black-Scholes model to estimate the grant date fair value are as follows:


	Year Ended December 31,
	2025	2024	2023
Risk-free interest rate	3.77% - 4.42%	3.94 - 4.36%	3.50 - 4.01%
Dividend yield	0%	0%	0%
Volatility	70.32% - 73.11%	71.91 - 77.01%	68.4 - 71.0%
Expected terms (years)	2.25 - 6.25	3.81 - 6.08	3.81 - 6.08

Schedule of Unvested Restricted Stock Units Activity

The following table summarizes the Company’s RSU activity:


	Number of Stock Units (in thousands)			Weighted Average Grant Date Fair Value Per Share
Unvested Balance at December 31, 2024		3,961		$	53.19
Granted		3,343			27.41
Vested		(1,487	)		50.18
Forfeited		(1,084	)		45.05
Unvested Balance at December 31, 2025		4,733		$	37.69

Market-Based RSUs [Member]

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Summary of Assumption Used to Estimate Units Weighted Average Grant Date Fair Value

The table below sets forth the weighted average grant date fair value assumptions used to value the rTSR PSUs:


	Year Ended December 31,
	2025
Risk-free interest rate	4.50%
Dividend yield	0%
Volatility	72.20%

Schedule of Unvested Restricted Stock Units Activity

The following table summarizes the Company’s rTSR PSU activity:


	Number of Stock Units (in thousands)			Weighted Average Grant Date Fair Value Per Share
Unvested Balance at December 31, 2024		—		$	—
Granted		646			44.04
Vested		—			—
Forfeited		(99	)		44.04
Unvested Balance at December 31, 2025		547		$	44.04

Performance-Based RSUs [Member]

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Schedule of Unvested Restricted Stock Units Activity

The following table summarizes the Company’s performance-based RSU activity:


	Number of Stock Units (in thousands)			Weighted Average Grant Date Fair Value Per Share
Unvested Balance at December 31, 2024		—		$	—
Granted		743			19.39
Vested		—			—
Forfeited		(31	)		19.39
Unvested Balance at December 31, 2025		712		$	19.39

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Section 50
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480483/718-10-35-1D

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147480483/718-10-35-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Publisher FASB
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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Reference 29: http://www.xbrl.org/2003/role/disclosureRef
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Reference 30: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Prepaid and Other Current Assets

12 Months Ended

Dec. 31, 2025

Prepaid Expense and Other Assets, Current [Abstract]

Prepaid and Other Current Assets

5. Prepaid and Other Current Assets

Prepaid and other current assets consisted of the following as of December 31, 2025 and 2024 (in thousands):


	December 31,
	2025		2024
Down payments for inventory	$	2,201	$	1,080
Prepaid research and development		22,096		7,780
Other prepaid assets		9,515		9,508
Royalties receivable		496		4,525
Receivable from collaboration agreement		2,442		2,272
Deposits and other current assets		1,553		4,847
Total prepaid and other current assets	$	38,303	$	30,012

Leases

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Leases

8. Leases

The underlying assets of the Company’s leases primarily relate to office space leases and certain equipment leases. The Company determines if an arrangement qualifies as a lease at its inception.

As of December 31, 2025 and 2024, all leases were classified as operating leases. Additional information related to the operating leases is as follows (in thousands):


	December 31,
	2025			2024
Right-of-use assets	$	18,195		$	16,083
Operating lease liabilities	$	19,034		$	16,954
Weighted average remaining term in years		3.31			2.73
Weighted average discount rate used to measure outstanding lease liabilities		6.52	%		6.20	%

For the years ended December 31, 2025, 2024, and 2023, the total lease cost for operating leases was approximately $10.5 million, $10.2 million, and $7.0 million, respectively.

Supplemental cash flow information related to operating leases for the years ended December 31, 2025, 2024 and 2023 is as follows (in thousands):


	2025		2024		2023
Operating cash flows from operating leases	$	10,471	$	9,263	$	7,939
Operating lease assets obtained in exchange for lease obligations	$	6,457	$	—	$	2,700

The maturity of the Company’s operating lease liabilities as of December 31, 2025 are as follows (in thousands):


2026	$	7,940
2027		5,808
2028		3,581
2029		3,324
2030 and thereafter		373
Total future minimum lease payments		21,026
Less imputed interest		(1,992	)
Total operating lease liabilities	$	19,034

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following as of December 31, 2025 and 2024 (in thousands):


	December 31,
	2025		2024
Accrued research and development	$	16,995	$	22,782
Accrued royalties		7,409		7,147
Accrued payroll liabilities		38,503		40,888
Accrued goods received not invoiced		21,248		638
Product revenue reserves		53,247		45,145
Commercial costs		25,907		20,610
Other		2,740		2,974
Total accrued expenses	$	166,049	$	140,184

Net Income/(Loss) per Common Share - Summary of Potential Common Shares that were Excluded from Calculation of Diluted Net Income/(Loss) Per Share Due to Anti-Dilutive Effect (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	9,989	14,389	15,344
Convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	0	2,379	2,379
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	6,506	8,048	8,664
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3,483	3,962	4,301

Segment Information

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Segment Information

16. Segment Information

The Company operates as a single reportable and single operating segment, which is the development and commercialization of treatments across a broad range of diseases driven by complement. The Company defines its segment on the basis in which internally reported financial information is regularly reviewed by CODM to analyze financial performance, make decisions, and allocate resources. The Company’s CODM reviews consolidated net income/(loss) for purposes of assessing performance, making operating decisions, strategically allocating future resources, and planning and forecasting for future periods.

The following table presents information about reported segment revenue, segment loss, and significant segment expenses as provided to the CODM with respect to the Company’s single operating segment for the years ended December 31, 2025, 2024 and 2023:


	Year Ended December 31,
	2025			2024			2023
Revenue	$	1,003,782		$	781,367		$	396,591
Less:
Internal research and development costs		88,182			91,881			121,931
Internal selling, general and administrative costs		180,833			162,874			176,778
External commercial costs		228,986			229,991			230,166
External research and development costs		167,567			194,422			186,812
External general and administrative costs		76,548			35,327			33,570
Other segment items (1)		102,369			121,842			59,237
Share-based compensation expense		104,003			114,128			105,945
Interest income		(13,143	)		(12,773	)		(20,933	)
Interest expense		44,327			40,391			29,581
Income tax expense		1,722			1,162			2,132
Net income/(loss)	$	22,388		$	(197,878	)	$	(528,628	)

(1)

Other segment items include cost of sales, loss on conversion of debt, and other expenses.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
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+ Details

Long-term Debt - Schedule of Outstanding Balance of Convertible Notes (Detail) - Convertible Senior Notes Due 2026 [Member] - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Principal	$ 93,897	$ 93,897
Less: debt discount and issuance costs, net	(235)	(556)
Net carrying amount	$ 93,662	$ 93,341

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References + Details

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References

+ Details

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Summary of Product Revenue Allowance and Reserve Categories (Parenthetical) (Details) $ in Millions	Dec. 31, 2025 USD ($)
GPO Chargebacks [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Product revenue allowances and reserves	$ 5.4

Segment Information (Tables)

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Schedule of segment financial information


	Year Ended December 31,
	2025			2024			2023
Revenue	$	1,003,782		$	781,367		$	396,591
Less:
Internal research and development costs		88,182			91,881			121,931
Internal selling, general and administrative costs		180,833			162,874			176,778
External commercial costs		228,986			229,991			230,166
External research and development costs		167,567			194,422			186,812
External general and administrative costs		76,548			35,327			33,570
Other segment items (1)		102,369			121,842			59,237
Share-based compensation expense		104,003			114,128			105,945
Interest income		(13,143	)		(12,773	)		(20,933	)
Interest expense		44,327			40,391			29,581
Income tax expense		1,722			1,162			2,132
Net income/(loss)	$	22,388		$	(197,878	)	$	(528,628	)

(1)

Other segment items include cost of sales, loss on conversion of debt, and other expenses.

Long-term Debt - Additional Information (Detail)				12 Months Ended
Long-term Debt - Additional Information (Detail)	Feb. 27, 2024 USD ($)	May 12, 2020 USD ($)	Sep. 16, 2019 USD ($)	Dec. 31, 2025 USD ($) Days $ / shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2024 USD ($)	Mar. 08, 2024 $ / shares	Sep. 11, 2019 CounterParty $ / shares
Capped Call Transactions [Member]
Debt Instrument [Line Items]
Volume-weighted average price per share \| $ / shares								$ 64.11
Proceeds from issuance of common stock	$ 98,800,000
Number of counterparties \| CounterParty									2
Initial conversion price \| $ / shares									$ 39.4625
Initial cap price \| $ / shares									$ 63.14
Convertible Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, stated percentage			3.50%
Debt instrument, due and payment description				The Convertible Notes are senior unsecured obligations of the Company and bear interest at a rate of 3.5% per year, payable semi-annually in arrears on March 15 and September 15 of each year, beginning on March 15, 2020.
Debt instrument, frequency of periodic payment				semi-annually
Credit facility maturity date			Sep. 15, 2026
Threshold trading days \| Days				20
Threshold consecutive trading days \| Days				30
Threshold percentage of stock price trigger				130.00%
Redemption period, start date				Sep. 20, 2023
Redemption price, percentage				100.00%
Convertible Senior Notes Due 2026 [Member] \| Prior to March 15, 2026 Convertible [Member]
Debt Instrument [Line Items]
Threshold trading days \| Days				20
Threshold consecutive trading days \| Days				30
Threshold percentage of stock price trigger				130.00%
Trading price per principal amount				$ 1,000
Convertible Senior Notes Due 2026 [Member] \| Prior to March 15, 2026 Convertible [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Threshold percentage of stock price trigger				98.00%
Convertible Senior Notes Due 2026 [Member] \| Common Stock [Member]
Debt Instrument [Line Items]
Terms of conversion				The Convertible Notes are convertible into shares of the Company’s common stock at an initial conversion rate of 25.3405 shares per $1,000 principal amount of Convertible Notes (equivalent to an initial conversion price of approximately $39.4625 per share of common stock). The conversion rate is subject to customary anti-dilution adjustments. In addition, following certain events that occur prior to the maturity date or if the Company deliver a notice of redemption, the Company will increase the conversion rate for a holder who elects to convert its Convertible Notes in connection with such corporate event or a notice of redemption, as the case may be, in certain circumstances as provided in the Indenture.
Conversion ratio				0.0253405
Conversion price \| $ / shares				$ 39.4625
Convertible Senior Notes Due 2026 [Member] \| 2019 Convertible Notes [Member]
Debt Instrument [Line Items]
Net proceeds from the sale of the notes			$ 212,900,000
Payment of convertible debt discounts and commissions			6,600,000
Payment of convertible debt offering expenses			500,000
Payments of transactions cost			28,400,000
Convertible Senior Notes Due 2026 [Member] \| 2020 Convertible Notes [Member]
Debt Instrument [Line Items]
Net proceeds from the sale of the notes		$ 322,900,000
Payment of convertible debt discounts and commissions		5,700,000
Payment of convertible debt offering expenses		300,000
Payments of transactions cost		43,100,000
Convertible Senior Notes Due 2026 [Member] \| 2020 Convertible Notes [Member] \| Exchange Agreements [Member]
Debt Instrument [Line Items]
Convertible notes held in treasury				$ 425,400,000			$ 425,400,000
Convertible Senior Notes Due 2026 [Member] \| 2020 Convertible Notes [Member] \| Common Stock [Member] \| Exchange Agreements [Member]
Debt Instrument [Line Items]
Aggregate principal amount converted into shares \| shares					12,926,104	12,926,104
Convertible Senior Notes Due 2026 [Member] \| 2019 Convertible Notes and 2020 Convertible Notes [Member] \| Exchange Agreements [Member]
Debt Instrument [Line Items]
Aggregate principal amount converted					$ 425,400,000	$ 425,400,000
Convertible Senior Notes Due 2026 [Member] \| Capped Call Transactions [Member]
Debt Instrument [Line Items]
Call transactions remaining is a notional amount				$ 93,900,000
Convertible Senior Notes Due 2026 [Member] \| Private Offering [Member] \| 2019 Convertible Notes [Member]
Debt Instrument [Line Items]
Principal amount			$ 220,000,000.0
Convertible Senior Notes Due 2026 [Member] \| Private Offering [Member] \| 2020 Convertible Notes [Member]
Debt Instrument [Line Items]
Principal amount		$ 300,000,000.0

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2025
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”).
Revenue Recognition	Revenue Recognition The Company’s revenues consist of product sales of EMPAVELI and SYFOVRE and revenue derived from its collaboration arrangement with Sobi. See Note 10, License and Collaboration Agreements for further discussion related to the Sobi Collaboration Agreement. The Company accounts for contracts with its customers in accordance with ASC Topic 606, Revenue from Contracts with Customers, (“ASC 606”). Pursuant to ASC 606, for arrangements or transactions between participants determined to be within the scope of the contracts with customers guidance, the Company performs the following five steps to determine the appropriate amount of revenue to be recognized as the Company fulfills its obligations: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. Revenue is recognized when, or as, the Company satisfies a performance obligation by transferring a promised good or service to a customer. An asset is transferred when, or as, the customer obtains control of that asset. For performance obligations that are satisfied over time, the Company recognizes revenue using an input or output measure of progress that best depicts the satisfaction of the relevant performance obligation.
Product Revenue	Product Revenue The Company’s revenue from net product sales related to EMPAVELI and SYFOVRE are primarily recognized in the United States. The Company sells EMPAVELI and SYFOVRE principally through arrangements with specialty pharmacies (“SPs”) and specialty distributors (“SDs”), who are the Company’s customers. The customers subsequently resell the product to patients and health care providers. The Company applies the ASC 606 five step process discussed above to the contracts with SPs and SDs. Product revenues are recognized when the customers take control of the product, which typically occurs upon delivery to the customers. The Company recognizes revenue from product sales at the net sales price which includes estimates of variable consideration for which reserves are established and reflects each of these as a reduction to revenue. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which the Company is entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from estimates, the Company may need to adjust its estimates, which would affect net revenue in the period of adjustment. The following are the Company’s significant categories of variable consideration: Fees and Patient Assistance Fees Distribution Fees: Distribution fees include distribution service fees paid to SDs based on a contractually fixed percentage of the wholesale acquisition cost (WAC). These fees are directly related to the storage, handling and distribution of product to customers, and are therefore inseparable from the product. Distribution fees are recorded as an offset to revenue based on contractual terms at the time revenue from the sale is recognized. Credit Card Fees: SDs will sell downstream to customers who may pay for product via credit card. The Company will reimburse its SDs for the credit card fees incurred as a result of SDs accepting credit cards as a form of payment from the downstream customers. Credit card fees are recorded as an offset to revenue based on the average aggregate credit card rate as a percentage of SD sales at the time revenue from the sale is recognized. Patient Assistance Copay: Other incentives include voluntary patient assistance programs, such as the Company’s co-pay assistance program, which are intended to provide financial assistance to qualified commercially-insured patients with prescription drug co-payments required by payors. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability. Government, Other Rebates and Chargebacks Rebates Government Rebates: The Company’s products are subject to pricing limits under certain federal government programs. Qualifying entities (i.e., end-users) purchase products from the Company’s customers at their qualifying discounted price. The chargeback amount the Company incurs represents the difference between the Company’s contractual sales price to the customer, and the end-user’s applicable discounted purchase price under the government program. Manufacturer Discount Program: The Company also participates in the Manufacturer Discount program, a federal program where the Company is required to provide discounts on drugs dispensed to eligible Medicare Part D patients. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability. Other Rebates and Chargebacks: The Company contracts with certain organizations, primarily group purchasing organizations ("GPOs") and pharmacy benefit managers, for the payment of rebates with respect to purchase of the Company's products by the end users. The Company estimates these rebates and records such estimates in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability. GPOs purchase from SDs at a discounted price. SDs charge back to the Company the difference between the price initially paid by SDs and the discounted price paid to SDs by the GPOs. The Company issues credit notes for the chargeback which are applied against amounts due from the SD. Returns Consistent with industry practice, the Company offers SPs and SDs limited product return rights for product damaged in shipping or shipped in error, short-dated, expired, recalled, or discontinued products; provided that the return is within a specified period around the product expiration date as set forth in the applicable individual distribution agreement. The Company does not allow product returns for product that has been dispensed to a patient. As the Company receives inventory reports from SPs and SDs and has visibility into the inventory distribution channel, it is able to make a reasonable estimate of future potential product returns based on this on-hand channel inventory data and sell-through data obtained from SPs and SDs. In arriving at its estimate for product returns, the Company also considers historical product returns and the underlying product demand.
Licensing and Other Revenue	Licensing and Other Revenue The Company analyzes license and collaboration arrangements pursuant to FASB ASC Topic 808, Collaborative Arrangement Guidance and Considerations, (“ASC 808”) to assess whether such arrangements, or transactions between arrangement participants, involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities or are more akin to a vendor-customer relationship. In making this evaluation, the Company considers whether the activities of the collaboration are considered to be distinct and deemed to be within the scope of the collaborative arrangement guidance or if they are more reflective of a vendor-customer relationship and, therefore, within the scope of ASC 606. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For elements of collaboration arrangements that are not accounted for pursuant to guidance in ASC 606, an appropriate recognition method is determined and applied consistently, generally by analogy to the revenue from contracts with customers guidance. Amounts related to transactions with a counterparty in a collaborative arrangement that is not a customer are presented as collaboration revenue and in a separate line item from revenue recognized from contracts with customers, if any, in the consolidated statements of operations. Pursuant to ASC 606, for arrangements or transactions between arrangement participants determined to be within the scope of the contracts with customers guidance, the Company performs the five-step process discussed above to determine the appropriate amount of revenue to be recognized as the Company fulfills its obligations. The Company evaluates the performance obligations promised in the contract that are based on goods and services that will be transferred to the customer and determine whether those obligations are both (i) capable of being distinct and (ii) distinct in the context of the contract. Goods or services that meet these criteria are considered distinct performance obligations. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each arrangement that includes variable consideration, the Company evaluates the amount of potential transaction price and the likelihood that the transaction price will be received. The Company utilizes either the most likely amount method or expected value method to estimate the amount expected to be received based on which method best predicts the amount expected to be received. The amount of variable consideration that is included in the transaction price may be constrained and is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and, if so, these options are considered performance obligations. The Company has not currently identified any such material rights. Revenue is recognized when, or as, the Company satisfies a performance obligation by transferring a promised good or service to a customer. An asset is transferred when, or as, the customer obtains control of that asset. For performance obligations that are satisfied over time, the Company recognizes revenue using an input or output measure of progress that best depicts the satisfaction of the relevant performance obligation. After contract inception, the transaction price is reassessed at every period end and updated for changes such as resolution of uncertain events. Any change in the overall transaction price is allocated to the performance obligations on the same methodology as at contract inception.
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker (“CODM”) is the chief executive officer (“CEO”). The Company manages its operations as a single operating segment. See Note 16, Segment Information, for additional information.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities in the Company’s consolidated financial statements and the accompanying notes. These estimates are based on historical experience and various other assumptions believed to be reasonable under the circumstances. Such estimates are used in the following areas, among others: accrued research and development expenses, reserves for variable consideration and reserves for excess or obsolete inventories. Actual results may differ from those estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company is required to disclose information on the fair value of financial instruments and inputs that enable an assessment of the fair value. The three levels of the fair value hierarchy prioritize valuation inputs based upon the observable nature of those inputs as follows: Level 1 – Quoted prices in active markets for identical assets or liabilities; Level 2 – Inputs other than quoted prices included within level 1 that are observable for the asset or liability, either directly or indirectly; Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. The Company’s financial instruments, in addition to those presented in Note 7, Long-term Debt, and Note 9, Fair Value Measurements, include cash and cash equivalents, accounts payable and accrued liabilities. Management believes that the carrying amounts of cash and cash equivalents, accounts payable and accrued expenses approximate the fair value due to the short-term nature of those instruments.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers highly-liquid investments with original maturities of three months or less to be cash equivalents. The Company holds cash in highly-liquid bank accounts and invests excess cash in money market funds.
Accounts Receivable	Accounts Receivable The Company’s accounts receivable are inclusive of receivables from its product sales to customers. They are generally stated at the invoiced amount and do not bear interest. The accounts receivable from product sales represent receivables due from the Company’s SPs or SDs. Payment terms are generally 30-65 days for EMPAVELI and 60-150 days for SYFOVRE. The Company monitors the financial performance and creditworthiness of its customers and provides reserves against trade receivables for expected credit losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are written-off against the established reserve. As of December 31, 2025 and 2024, the Company did not have an allowance for credit losses. The Company has had no historical write-offs of its accounts receivable as of December 31, 2025 and 2024. The Company has an agreement (the “Factoring Agreement”) to sell certain trade accounts receivable to a third-party financial institution at a discount to the invoiced amount. Under the Factoring Agreement, the maximum amount of outstanding accounts receivables sold at any time is $100.0 million. The Company accounts for the transfer of trade accounts receivable under the Factoring Agreement as a sale in accordance with ASC 860, Transfers and Servicing, because effective control and risk associated with the transferred accounts receivable is passed to the third-party. Accordingly, the Company derecognizes the sold trade accounts receivable from the consolidated balance sheets. Cash proceeds related to the accounts receivable sold are included in cash from operating activities in the consolidated statements of cash flows. Any discounts or fees incurred in connection with the sales are recorded within “Selling, general and administrative expenses" in the consolidated statements of operations and comprehensive income/(loss). Pursuant to the Factoring Agreement, the Company performs certain collection and administrative functions for the receivable sold. The fair value of these administrative services is not material and therefore, the Company has not recorded any servicing assets or liabilities associated with the Factoring Agreement. See Note 3, Product Revenues, Accounts Receivable, and Reserves for Product Sales for additional information.
Inventory	Inventory Inventory is recorded at the lower of cost or net realizable value, with cost determined on a first-in, first-out basis. Inventory costs include third-party contract manufacturing, third-party packaging services, labor, overhead and freight. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and writes down any excess and obsolete inventories to their estimated realizable value. Expenses incurred related to excess and obsolete inventories are recorded within cost of sales. The determination of whether inventory costs will be realizable requires estimates by management. Provisions for potentially obsolete or slow-moving inventory are made based on the Company’s analysis of product dating, inventory levels, historical obsolescence and future sales forecasts. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required which would be recorded as a cost of sales in the consolidated statements of operations and comprehensive income/(loss). Inventory not expected to be sold within the Company’s normal operating cycle is classified as long-term inventory on the consolidated balance sheets. Prior to regulatory approval of its product candidates, the Company expenses costs associated with the manufacturing of its product candidates to research and development expense unless the Company is reasonably certain such costs have future commercial use and net realizable value. When the Company believes regulatory approval and subsequent commercialization of its product candidates is probable, and the Company also expects future economic benefit from the sales of the product candidates to be realized, the Company will then capitalize the costs of production as inventory. Inventory that can be used in either the production of clinical or commercial product is expensed as research and development expense when selected for use in a clinical manufacturing campaign. Shipping and handling costs for product shipments are recorded as incurred in cost of sales along with costs associated with manufacturing the product and any inventory write-downs.
Foreign Currency	Foreign Currency The functional currency of each of the Company’s subsidiaries is its local currency, except for the wholly owned subsidiaries Apellis Europe B.V. and Apellis International GmbH where the functional currency is the U.S. dollar. Revenues and expenses of the subsidiaries have been translated into U.S. dollars at average exchange rates prevailing during the respective periods. Assets and liabilities have been translated at the rates of exchange on the balance sheet date. The resulting translation gain and loss adjustments are recorded directly as a separate component of stockholders’ equity.
Research and Development	Research and Development Costs incurred in connection with research and development activities are expensed as incurred. Research and development expenses include (i) employee-related expenses, including salaries, benefits, travel and share-based compensation expense; (ii) external research and development expenses incurred under arrangements with third parties, such as contract research and contract manufacturing organizations, investigational sites and consultants, including share-based compensation expense for consultants; (iii) the cost of acquiring, developing and manufacturing clinical study materials; and (iv) costs associated with preclinical and clinical activities and regulatory operations. The Company enters into consulting, research and other agreements with commercial entities, researchers, universities and others for the provision of goods and services. Such arrangements are generally cancellable upon reasonable notice and payment of costs incurred. Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided by the Company’s clinical sites and vendors. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly. Under the Sobi Collaboration Agreement, the Company may receive reimbursements from Sobi for certain agreed upon developmental activities. The Company presents such reimbursements as contra-research and development expense based on an evaluation of the nature and contractual terms of the arrangement and the nature of the Company’s business operations.
Selling, General and Administrative	Selling, General and Administrative Costs incurred in connection with selling, general and administrative activities are expensed as incurred. Selling, general and administrative expenses consist primarily of costs associated with the commercialization of approved products and general and administrative costs to support operations, including salaries, bonuses, benefits and share-based compensation. Selling expenses include product marketing, sales operations costs, and other costs incurred to support the Company’s sales efforts. General and administrative expenses include corporate support functions such as executive management, finance and accounting, business development, legal, human resources, information technology, and associated external costs to support those functions. Other significant costs include costs associated with medical affairs, drug safety and pharmacovigilance, quality and regulatory costs not otherwise included in research and development expenses, legal fees relating to patent and corporate matters, and fees for accounting and consulting services. Marketing and advertising costs include marketing literature, promotional activities, conferences and seminars, branding and sponsorships. For the years ended December 31, 2025, 2024 and 2023, the Company incurred advertising costs of $91.8 million, $83.3 million, and $86.5 million, respectively.
Income Taxes	Income Taxes The provision for income taxes includes federal, state, local and foreign taxes. Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions using a more likely than not threshold for recognizing and resolving uncertain tax positions. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of December 31, 2025 and 2024, the Company did not have any significant uncertain tax positions
Share Based Compensation - Option	Share-Based Compensation The Company’s share-based compensation program allows for grants of stock options and restricted stock units. The Company measures share-based compensation cost at the grant date based on the fair value of the option and restricted stock units, and recognizes the expense related to awards on a straight-line basis over the requisite service period, which is typically the vesting period. Expense for awards with performance conditions is estimated and adjusted on a quarterly basis based upon the assessment of the probability that the performance condition will be met, and is expensed using an accelerated method over the term of the award. Forfeitures are recognized as they occur. The Company estimates the fair value of each option using the Black-Scholes option pricing model that considers the fair value of its common stock, the exercise price, the expected life of the option, the expected volatility of its common stock, expected dividends on its common stock, and the risk-free interest rate over the expected life of the option. The Company uses the simplified method described in the SEC’s Staff Accounting Bulletin No. 107, Share-Based Payment, to determine the expected life of the option grants. The estimate of expected volatility is based on the Company’s historical volatility over a period commensurate with the expected term of the option. The Company has never declared or paid any cash dividends on its common stock and does not expect to do so in the foreseeable future. Accordingly, it uses an expected dividend yield of zero. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant valuation for a period commensurate with expected term of the option. Additionally, the Company uses a Monte Carlo simulation model to calculate the estimated fair value on the date of grant related to awards with market-based conditions. For awards with performance conditions, the Company assesses the probability of achievement at each reporting date to determine recognition of compensation expense.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk include cash and cash equivalents and accounts receivable. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and the issuers of its cash equivalents. The Company maintains its cash and cash equivalents with highly-rated financial institutions. At times, such amounts may exceed federally-insured limits. The Company has not experienced any losses on its deposits since inception, and management believes that minimal credit risk exists with respect to these financial institutions. Billings to large specialty pharmacies and specialty distributors account for the majority of the Company’s accounts receivable, and collateral is generally not required from these customers. To mitigate credit risk, the Company monitors the financial performance and credit-worthiness of its customers. See Note 3, Product Revenues, Accounts Receivable, and Reserves for Product Sales for additional information.
Net Income/(Loss) per Share	Net Income/(Loss) per Share Basic net income/(loss) per share is calculated by dividing the net income or loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net income/(loss) per share is computed by dividing the net income or loss by the weighted-average number of shares of common stock, plus potentially dilutive securities outstanding for the period, as determined in accordance with the treasury stock, if-converted, or contingently issuable accounting methods, depending on the nature of the security. For purposes of the diluted net income/(loss) per share calculation, stock options, restricted stock units (“RSUs”), shares potentially issuable in connection with the Company’s employee stock purchase plan (“ESPP”) and convertible notes are considered potentially dilutive securities and included to the extent that their addition is not antidilutive.
Recent Accounting Pronouncements Issued not yet Adopted / Recently Adopted Accounting Pronouncements	Recent Accounting Pronouncements issued not yet adopted In December 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2025‑12, Codification Improvements, which includes targeted amendments to clarify, correct, and improve various aspects of the FASB Accounting Standards Codification. The ASU is effective for annual periods beginning after December 15, 2026, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements. In December 2025, the FASB issued ASU 2025‑11, Interim Reporting (Topic 270): Improvements to Interim Disclosure Requirements, which clarifies disclosure requirements for interim financial statements. The ASU is effective for interim reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the impact of this guidance on its interim financial statement disclosures. In September 2025, the “FASB issued “ASU 2025-06, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Improvements to Capitalization of Software Development Costs, which updates the accounting guidance for internal-use software costs and removes references to prescriptive project stages. The ASU is effective for annual periods beginning after December 15, 2027, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the timing of adoption and the impact of the new guidance on the consolidated financial statements and related disclosures. In July 2025, the FASB issued ASU 2025-05, Measurement of Credit Losses for Accounts Receivable and Contract Assets, which provides a practical expedient to measure credit losses on accounts receivable and contract assets. The ASU is effective for annual periods beginning after December 15, 2025, and interim periods within those annual reporting periods. Early adoption is permitted. The Company is currently evaluating the timing of the adoption and the impact of the new guidance on the consolidated financial statements and related disclosures. In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, which requires additional disclosure of the nature of expenses included in the income statement. The standard requires disclosures about specific types of expenses included in the expense captions presented in the income. This ASU is effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027, with early adoption permitted. The requirements should be applied on a prospective basis while retrospective application is permitted. The Company is currently evaluating the impact that the adoption of this guidance will have on its disclosures. Recently adopted accounting pronouncements In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures. This standard is an amendment to the accounting guidance on income taxes which establishes incremental disaggregation of income tax disclosure pertaining to the effective tax rate reconciliation and income taxes paid. The amendments in this update are required to be applied on a prospective basis with the option to apply it retrospectively. The guidance is effective for annual periods beginning after December 15, 2024. The Company adopted ASU 2023-09 for the year ended December 31, 2025, and applied the new disclosure requirements retrospectively to the current annual period. The adoption of this standard did not have a material impact on the Company's consolidated financial position or results of operation. Refer to Note 12, Income Taxes in the accompanying notes to the consolidated financial statements for further details.

Segment Information - Additional Information (Detail)	12 Months Ended
Segment Information - Additional Information (Detail)	Dec. 31, 2025 Segment
Segment Reporting [Abstract]
Number of operating segment	1
Number of reportable segments	1
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	The Company defines its segment on the basis in which internally reported financial information is regularly reviewed by CODM to analyze financial performance, make decisions, and allocate resources. The Company’s CODM reviews consolidated net income/(loss) for purposes of assessing performance, making operating decisions, strategically allocating future resources, and planning and forecasting for future periods.
Segment Reporting, Expense Information Used by CODM, Type [Extensible Enumeration]	Net Income (Loss)

Development Liability - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	May 13, 2024	May 31, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from credit facility				$ 365,454
Loss on extinguishment of development liability				1,949
Interest expense			$ 44,327	$ 40,391	$ 29,581
Sixth Financing Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from credit facility	$ 326,500	$ 326,500

Net Income/(Loss) per Common Share - Summary of Basic and Diluted Net Income/(Loss) per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Numerator:
Net Income (Loss)	$ 22,388	$ (197,878)	$ (528,628)
Adjustment - Interest expense on Convertible Notes	3,607	0	0
Adjusted net income/(loss)	$ 25,995	$ (197,878)	$ (528,628)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic	126,145	123,905	118,678
Weighted-average number of common shares used in net income/(loss) per common share - diluted	129,855	123,905	118,678
Net income/(loss) per common share - basic	$ 0.18	$ (1.6)	$ (4.45)
Net income/(loss) per common share - diluted	$ 0.2	$ (1.6)	$ (4.45)
Convertible notes
Denominator:
Incremental common shares attributable to conversion of debt	2,379	0	0
Stock options to purchase common stock
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements	967	0	0
Unvested restricted stock units
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements	346	0	0
Shares expected to be purchased under employee stock purchase plan
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements	18	0	0

Prepaid and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2025

Prepaid Expense and Other Assets, Current [Abstract]

Summary of Prepaid and Other Current Assets

Prepaid and other current assets consisted of the following as of December 31, 2025 and 2024 (in thousands):


	December 31,
	2025		2024
Down payments for inventory	$	2,201	$	1,080
Prepaid research and development		22,096		7,780
Other prepaid assets		9,515		9,508
Royalties receivable		496		4,525
Receivable from collaboration agreement		2,442		2,272
Deposits and other current assets		1,553		4,847
Total prepaid and other current assets	$	38,303	$	30,012

License and Collaboration Agreements - Additional Information (Detail) $ in Thousands		1 Months Ended					3 Months Ended	12 Months Ended			33 Months Ended	60 Months Ended
	Nov. 30, 2020 USD ($)	Sep. 30, 2025 USD ($)	Aug. 31, 2025 USD ($)	Jun. 30, 2022	Apr. 30, 2022 USD ($)	Jun. 30, 2021 Program	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($) License	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2025 USD ($) License	Dec. 31, 2025 USD ($) License	Jan. 31, 2026 USD ($)	Jul. 01, 2025 USD ($) Price	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalties receivable								$ 496	$ 4,525		$ 496	$ 496
Revenue								1,003,782	781,367	$ 396,591
Accrued expenses								166,049	140,184		166,049	166,049
Licensing and other revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue								314,399	71,413	30,310
SYFOVRE [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue								586,934	611,863	275,248
Royalty expense								19,100	19,800	8,900
Regulatory milestone payments											7,300
Empaveli And Aspaveli [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalty expense								7,300	6,400	4,800
Swedish Orphan Biovitrum AB (Publ) [Member] \| Aspaveli [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalty revenue								13,200	18,400	$ 10,000
Collaboration and License Agreement [Member] \| Swedish Orphan Biovitrum AB (Publ) [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment	$ 250,000
Milestone payment received for achievement of regulatory development milestone					$ 50,000
Development cost reimbursement received								65,000
Waived Payment								$ 15,000
Royalties entitled to receive after first commercial sale of applicable licensed product period								10 years
Percentage of royalty payment obligation														90.00%
Revenue recognized								$ 26,200	53,000
Contract research and development expense								10,600	$ 9,900
Additional contra research and development expense recognized								65,000
Contract research and development reimbursement commitment								80,000
Percentage of royalty payment obligation reverted														100.00%
Caps intial purchase price \| Price														1.45
Collaboration and License Agreement [Member] \| Swedish Orphan Biovitrum AB (Publ) [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate milestone payments upon achievement of specified one time regulatory development and commercial milestone events																	$ 915,000
Development cost reimbursement								80,000
University of Pennsylvania [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Sublicense Payments												30,500
Development and Sales Milestone Paid												3,500
University of Pennsylvania [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate milestones payments								3,200			3,200	3,200
Milestone payments based on annual sales milestones								5,000
Total future minimum payments								$ 3,200			$ 3,200	$ 3,200
Royalty Agreement [Member] \| Swedish Orphan Biovitrum AB (Publ) [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment to be received														$ 275,000
Aggregate amount agreed to be received upon European Medicines Agency approval														$ 25,000
Royalty Agreement [Member] \| Swedish Orphan Biovitrum AB (Publ) [Member] \| Subsequent Event [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional aggregate amount agreed to be received upon agency approval													$ 25,000
Royalty Agreement [Member] \| Swedish Orphan Biovitrum AB (Publ) [Member] \| Licensing and other revenue [Member] \| Forecast [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue							$ 25,000
2010 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of licensed products \| License								2			2	2
2010 License Agreement [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate milestones payments								$ 1,700			$ 1,700	$ 1,700
Milestone payments based on annual sales milestones								2,500
Total future minimum payments								$ 1,700			$ 1,700	$ 1,700
Neonatal Fc Receptor [Member[ \| Beam [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment		$ 3,800
Neonatal Fc Receptor [Member[ \| Beam [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment received for achievement of regulatory development milestone			$ 168,800
Milestone payments based on annual sales milestones			$ 215,000
Research Collaboration Agreement [Member] \| Beam [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration agreement term						5 years
Number of research programs \| Program						6
Up-front non-refundable payment															$ 25,000	$ 50,000
Collaboration agreement maximum extendable term				2 years

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2025

Fair Value, Nonrecurring [Member]

Schedule of Financial Instruments and the Related Fair Value Hierarchy of the Valuation Techniques Utilized

The following table presents the fair value of the Company’s financial instruments that are measured at fair value on a recurring basis as of December 31, 2025 and 2024 (in thousands):


		December 31, 2025
Balance Sheet Classification:	Type of Instrument	Level 1		Level 2		Level 3		Total
Financial Assets:
Cash and cash equivalents:	Money market funds	$	349,615	$	—	$	—	$	349,615
Total Financial Assets		$	349,615	$	—	$	—	$	349,615

		December 31, 2024
Balance Sheet Classification:	Type of Instrument	Level 1		Level 2		Level 3		Total
Financial Assets:
Cash and cash equivalents:	Money market funds	$	276,868	$	—	$	—	$	276,868
Total Financial Assets		$	276,868	$	—	$	—	$	276,868

Product Revenues, Accounts Receivable, and Reserves for Product Sales (Tables)

12 Months Ended

Dec. 31, 2025

Product Revenues Accounts Receivable And Reserves For Product Sales [Abstract]

Schedule of Disaggregation of Product Revenue by Major Source

The table reflects net product revenue by major source for the following periods (in thousands):


			Year Ended December 31,
	Therapeutic Area	Key Indications	2025		2024		2023
Products:
EMPAVELI	Rare Disease	PNH, C3G (1), IC-MPGN (1)	$	102,449	$	98,091	$	91,033
SYFOVRE	Ophthalmology	GA		586,934		611,863		275,248
Total product revenue, net			$	689,383	$	709,954	$	366,281

(1) The FDA approved EMPAVELI for the treatment of C3G and primary IC-MPGN on July 28, 2025.

Summary of Product Revenue Allowance and Reserve Categories

The following table summarizes activity in each of the product revenue allowance and reserve categories as of December 31, 2025 (in thousands)::


	Fees and patient assistance			Government, Other Rebates, and Chargebacks (1)			Returns			Total
Ending balance at December 31, 2022	$	164		$	1,936		$	251		$	2,351
Provision related to sales in the current year		17,690			26,661			4,698			49,050
Adjustments related to prior period sales		(112	)		(1,223	)		(2,481	)		(3,817	)
Credits and payments made		(12,068	)		(18,476	)		(415	)		(30,960	)
Ending balance at December 31, 2023	$	5,674		$	8,898		$	2,053		$	16,625
Provision related to sales in the current year		46,506			89,094			3,936			139,536
Adjustments related to prior period sales		1,461			(19	)		(96	)		1,346
Credits and payments made		(42,052	)		(66,440	)		(3,870	)		(112,362	)
Ending balance at December 31, 2024	$	11,589		$	31,533		$	2,023		$	45,145
Provision related to sales in the current year		49,594			140,065			5,652			195,311
Adjustments related to prior period sales		298			(13	)		(382	)		(97	)
Credits and payments made		(48,707	)		(128,658	)		(4,380	)		(181,745	)
Ending balance at December 31, 2025	$	12,774		$	42,927		$	2,913		$	58,614

(1) As of December 31, 2025, GPO chargebacks of $5.4 million are presented in the consolidated financial statements as reductions to accounts receivable, net. The GPO chargebacks as of December 31, 2024, and 2023 were immaterial. All other gross-to-net adjustments are presented in the consolidated financial statements as accrued expenses.

Schedule of Customer Accounted for 10% of More of Gross Product Revenues and Accounts Receivable

Significant customers - Gross product revenues and product sales receivable from the Company’s customers who individually accounted for 10% of more of total gross product revenues and/or 10% or more of total product sales receivable consisted of the following:


	Percent of Total Gross Product Revenues
	Year Ended December 31,
	2025	2024	2023
Customer A	13%	13%	24%
Customer C	19%	19%	16%
Customer D	58%	59%	54%


	Percent of Product Sales Receivable
	As of December 31,
	2025	2024
Customer C	22%	29%
Customer D	66%	55%

Schedule of Factoring of Accounts Receivable and Associated Fees

Factoring of accounts receivable and associated fees for the years ended December 31, 2025, and 2024 were as follows (in thousands):


	December 31,			December 31,
	2025			2024
Accounts receivable sold	$	199,447		$	142,698
Less: factoring fees		(2,434	)		(1,700	)
Net cash proceeds	$	197,013		$	140,998

Commitments and Contingencies

12 Months Ended

Dec. 31, 2025

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

13. Commitments and Contingencies

The Company has certain non-cancelable purchase obligations related to the manufacturing of drug substance. The Company has agreed to purchase from Bachem Americas, Inc. a significant portion of its requirements for the pegcetacoplan drug substance. Under a commercial supply agreement with NOF Corporation (“NOF”), the Company has agreed to purchase activated polyethylene glycol derivative, or PEG, which is a component of pegcetacoplan. Under these agreements, as of December 31, 2025, the Company is obligated to pay up to an aggregate of $69.1 million to these vendors over the next three years. In September 2024, the Company terminated the minimum purchase obligation with NOF for 2025. As a result of this termination, the Company incurred an expense of $6.4 million, which is included in cost of sales on the consolidated statements of operations and comprehensive income/(loss). As the amount was not due until January 2026, it is included in current liabilities on the consolidated balance sheet as of December 31, 2025, and in other liabilities on the consolidated balance sheet as of December 31, 2024. The $6.4 million obligation was subsequently paid by the Company in the first quarter of 2026

In addition, the Company has other non-cancelable purchase agreements as of December 31, 2025, under which it is obligated to pay up to an aggregate of $6.7 million to vendors over the next three years.

The Company is a party to a master lease agreement under which the Company leases vehicles with initial terms of 36 months from the date of delivery. If the Company were unable to take delivery of a previously ordered vehicle, the Company may incur nominal fees.

Indemnifications—In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend indemnified parties for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future

payments the Company could be required to make under these provisions is not determinable. The Company has not incurred any cost to defend lawsuits or settle claims related to these indemnification provisions.

Legal—During the normal course of business, the Company may be a party to legal claims that may not be covered by insurance.

In March 2025, the United States District Court for the District Court of Massachusetts dismissed, without prejudice and without leave to amend, a putative class action complaint that was filed in August 2023 against the Company and certain current and former executive officers of the Company, which alleged, among other things, that the defendants violated Sections 10(b) and/or 20(a) of the Exchange Act and Rule 10b-5 promulgated thereunder by misrepresenting and/or omitting certain material facts related to the design of SYFOVRE’s clinical trials and the risks associated with SYFOVRE’s commercial adoption, and sought, among other relief, compensatory damages and equitable relief in favor of the alleged class against all defendants, including interest, and reasonable costs and expenses incurred by plaintiffs, including attorneys’ and expert fees. In April 2025, the plaintiffs filed an appeal to the United States Court of Appeals for the First Circuit, which conducted a hearing in January 2026.

In December 2024, purported stockholders filed putative stockholder derivative lawsuits in the United States District Court for the District of Massachusetts on behalf of the Company against the Company’s directors for breach of fiduciary duty, unjust enrichment, waste, and alleged violation of Section 14(a) of the Exchange Act related to the design of SYFOVRE’s clinical trials and the risks associated with SYFOVRE’s commercial adoption, and sought monetary and punitive damages, and costs, including attorneys’ fees. These cases were consolidated under the caption In re Apellis Pharmaceuticals, Inc. Derivative Litigation, No. 1:24-cv-13128-JEK in January 2025 and are stayed pending the outcome of the appeal in the United States Court of Appeals for the First Circuit of the dismissal of the securities class action.

The Company’s businesses may also be subject at any time to commercial disputes, product liability claims, personal injury claims, third-party subpoenas or various other lawsuits arising in the ordinary course of business, including intellectual property infringement, employment or investor matters, and the Company expects that this will continue to be the case in the future.

Segment Information - Schedule of Segment Revenue, Segment Profit or Loss and Significant Segment Expenses (Detail) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Dec. 31, 2023

Less:

Interest income

$ (13,143)

$ (12,773)

$ (20,933)

Interest expense

44,327

40,391

29,581

Income tax expense

1,722

1,162

2,132

Net income/(loss)

22,388

(197,878)

(528,628)

Reported Segment [Member]

Segment Reporting Information [Line Items]

Revenue

1,003,782

781,367

396,591

Less:

Internal research and development costs

88,182

91,881

121,931

Internal selling, general and administrative costs

180,833

162,874

176,778

External commercial costs

228,986

229,991

230,166

External research and development costs

167,567

194,422

186,812

External general and administrative costs

76,548

35,327

33,570

Other segment items

^[1]

102,369

121,842

59,237

Share-based compensation expense

104,003

114,128

105,945

Interest income

(13,143)

(12,773)

(20,933)

Interest expense

44,327

40,391

29,581

Income tax expense

1,722

1,162

2,132

Net income/(loss)

$ 22,388

$ (197,878)

$ (528,628)

[1]	Other segment items include cost of sales, loss on conversion of debt, and other expenses.

Net Income/(Loss) per Common Share

12 Months Ended

Dec. 31, 2025

Earnings Per Share [Abstract]

Net Income/(Loss) per Common Share

15. Net Income/(Loss) per Common Share

The following table presents the calculation of basic and diluted net income/(loss) per common share (amounts in thousands, except per share amounts):


	Year Ended December 31,
	2025		2024			2023
Basic net income/(loss) per share
Numerator:
Net income/(loss)	$	22,388	$	(197,878	)	$	(528,628	)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic		126,145		123,905			118,678
Net income/(loss) per common share - basic	$	0.18	$	(1.60	)	$	(4.45	)

Diluted net income/(loss) per share
Numerator:
Net income/(loss)	$	22,388	$	(197,878	)	$	(528,628	)
Adjustment - Interest expense on Convertible Notes		3,607		—			—
Adjusted net income/(loss)	$	25,995	$	(197,878	)	$	(528,628	)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic		126,145		123,905			118,678
Convertible notes		2,379		—			—
Stock options to purchase common stock		967		—			—
Unvested restricted stock units		346		—			—
Shares expected to be purchased under employee stock purchase plan		18		—			—
Weighted-average number of common shares used in net income/(loss) per common share - diluted		129,855		123,905			118,678
Net income/(loss) per common share - diluted	$	0.20	$	(1.60	)	$	(4.45	)

Shares outstanding presented below were excluded from the calculation of diluted net income/(loss) per share, prior to the use of the treasury stock method, as their effect is anti-dilutive (in thousands):


	Year Ended December 31,
	2025		2024		2023
Convertible notes		—		2,379		2,379
Stock options to purchase common stock		6,506		8,048		8,664
Unvested restricted stock units		3,483		3,962		4,301
Total		9,989		14,389		15,344

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating Activities
Net income/(loss)	$ 22,388	$ (197,878)	$ (528,628)
Adjustments to reconcile net income/(loss) to net cash used in operating activities:
Share-based compensation expense	104,003	114,128	105,945
Loss on extinguishment of development liability		1,949
Loss on disposal of fixed assets			120
Depreciation expense	1,558	1,797	1,784
Amortization of Discounts for Credit Facility and Convertible Notes	2,496	1,559	297
Accretion of discount to development liability		8,936	25,996
Changes in operating assets and liabilities:
Accounts receivable	(101,279)	(58,484)	(198,715)
Inventory	(15,267)	(10,755)	(60,647)
Prepaid and other current assets	(8,087)	31,213	12,373
Other assets	(4,061)	705	11,700
Right-of-use assets and lease liabilities	(34)	(277)	(80)
Accounts payable	18,223	1,089	170
Accrued expenses and other liabilities	25,387	18,152	34,950
Net cash provided by/(used in) operating activities	45,327	(87,866)	(594,735)
Investing Activities
Purchase of property and equipment	(313)	(403)	(773)
Proceeds from sale of fixed assets			99
Net cash used in investing activities	(313)	(403)	(674)
Financing Activities
Proceeds from credit facility		365,454
Payment of issuance cost for credit facility		(7,214)
Repayment of development liability		(326,533)	(55,500)
Proceeds from settlement of capped call		98,763
Proceeds from issuance of common stock, pre-funded warrant offering, net of issuance costs			384,387
Proceeds from exercise of stock options	5,545	14,316	71,274
Proceeds from issuance of common stock under employee share purchase plan	3,350	4,512	5,378
Payments of employee tax withholding related to equity-based compensation	(11)	(57)	(11,040)
Net cash provided by financing activities	8,884	149,241	394,499
Effect of exchange rate changes on cash, cash equivalents and restricted cash	1,250	(659)	135
Net increase (decrease) in cash, cash equivalents and restricted cash	55,148	60,313	(200,775)
Cash, cash equivalents and restricted cash at beginning of period	412,612	352,299	553,074
Cash, cash equivalents and restricted cash at end of period	467,760	412,612	352,299
Reconciliation of cash, cash equivalents and restricted cash to the consolidated balance sheets:
Cash and cash equivalents	466,233	411,290	351,185
Restricted cash	1,527	1,322	1,114
Total cash, cash equivalents, and restricted cash	467,760	412,612	352,299
Supplemental disclosure of cash flow information:
Cash paid for interest	$ 41,233	$ 29,368	$ 3,286

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets:
Intangible assets	$ 178,715	$ 177,244
Research and development capitalization	13,831	21,474
Contribution carryforward	8,782
Share-based compensation	43,966	38,494
Net operating loss carryforwards	306,448	312,672
Research and development credits	81,832	81,340
Orphan drug credits	43,129	48,015
Convertible debt	467	1,021
Fixed assets	370	194
Lease liability	3,972	3,026
Accruals	10,966	7,668
Deferred interest expense	4,234	1,974
Inventory reserves	42,051	31,476
UNICAP	(84)	1,806
Total deferred tax assets	738,679	726,404
Deferred tax liabilities:
Right-of-use asset	(3,863)	(2,821)
Total deferred tax liabilities	(3,863)	(2,821)
Net deferred tax assets before allowance:	734,816	723,583
Less valuation allowance	$ (734,816)	$ (723,583)

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2025	Dec. 31, 2024
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, issued	126,621,000	124,495,000
Common stock, outstanding	126,621,000	124,495,000

License and Collaboration Agreements

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

License and Collaboration Agreements

10. License and Collaboration Agreements

Sobi License and Collaboration Agreement

In October 2020, the Company and its subsidiaries, Apellis International GmbH (f/k/a Apellis Switzerland GmbH) and APL DEL Holdings, LLC, entered into a Collaboration and License Agreement (the “Sobi Collaboration Agreement”) with Sobi, concerning the development and commercialization of pegcetacoplan and specified other structurally and functionally similar compstatin analogues or derivatives for use systemically or for local non-ophthalmological administration (collectively referred to as the “Licensed Products”).

Under the Sobi Collaboration Agreement, the Company granted Sobi an exclusive (subject to certain retained rights of the Company), sublicensable license of certain patent rights and know-how to develop and commercialize Licensed Products in all countries outside of the United States.

The Company retains the right to commercialize Licensed Products in the United States, and, subject to specified limitations, to develop Licensed Products worldwide for commercialization in the United States.

Under the Sobi Collaboration Agreement, the Company and Sobi agreed to collaborate to develop Licensed Products for certain indications, including PNH, C3G, primary IC-MPGN and HSCT-TMA (collectively the “Initial Indications”), and any other indications subsequently agreed upon by the parties, for commercialization by or on behalf of the Company in the United States and by or on behalf of Sobi outside of the United States. If the parties do not agree to jointly pursue any development activities for the Licensed Products (whether for an Initial Indication or otherwise), the party proposing to pursue such activities may conduct such activities at its sole expense (with the non-proposing party having the right to obtain rights to the data generated by such development activities by paying a specified percentage of that expense), subject to agreed-upon exceptions that limit each party’s unilateral development rights. In July 2025, the Company and Sobi decided to discontinue development of systemic pegcetacoplan for Transplant-associated Thrombotic Microangiopathy (TA-TMA) (inclusive of HSCT-TMA), following completion of the Phase 2 study and a strategic assessment of the TA-TMA market landscape.

The initial development plan sets forth the initial development activities to be conducted by each of the Company and Sobi, with the Company bearing all costs incurred in conducting the activities set forth in such initial development plan, as well as certain specified additional costs that are not included in the initial development plan that may be incurred by the parties in developing Licensed Products for PNH in the European Union and the United Kingdom. The Company and Sobi formed several governance committees to oversee the development and manufacture, and to review and discuss the commercialization, of Licensed Products.

The Company shall supply Licensed Products to Sobi for development and for commercialization outside of the United States in accordance with a supply agreement between the parties. The Sobi Collaboration Agreement grants Sobi the right to perform drug product manufacturing of Licensed Products for development and for commercialization outside the United States and to manufacture drug substance under certain circumstances. For the years ended December 31, 2025 and 2024, the Company recognized revenue of $26.2 million and $53.0 million, respectively, for the supply of Licensed Products to Sobi, which is included in Licensing and other revenue on the consolidated statements of operations and comprehensive income/(loss).

Sobi paid the Company an upfront payment of $250.0 million in November 2020 and has agreed to pay up to an aggregate of $915.0 million upon the achievement of specified one-time regulatory and commercial milestone events, of which the Company received $50.0 million in April 2022 for the achievement of a regulatory development milestone in Europe. Sobi also agreed to reimburse the Company for up to $80.0 million in development costs for the Initial Indications (defined above), of which the Company received $65.0 million and waived the remaining payment of $15.0 million. The Company will also be entitled to receive tiered, double-digit royalties (ranging from high teens to high twenties) on sales of Licensed Products outside of the United States, subject to customary deductions and third-party payment obligations, until the latest to occur of: (i) expiration of the last-to-expire of specified licensed patent rights; (ii) expiration of regulatory exclusivity; and (iii) ten (10) years after the first commercial sale of the applicable Licensed Product, in each case on a Licensed Product-by-Licensed Product and country-by-country basis. Under the Sobi Collaboration Agreement, the Company remains responsible for its license fee obligations (including royalty obligations) to the Trustees of the University of Pennsylvania (“Penn”), as a licensor of the Company.

On July 1, 2025 (the “Closing Date”), Apellis Pharmaceuticals, Inc. and its subsidiaries Apellis International GmbH and APL DEL Holdings, LLC entered into a Royalty Buy-Down Agreement (the “Royalty Agreement”) with Sobi.

Under the Royalty Agreement, Sobi paid the Company an upfront payment of $275.0 million and agreed to pay up to an aggregate of $25.0 million upon the European Medicines Agency (“EMA”) approval of Aspaveli for C3G and primary IC-MPGN (collectively, the “purchase price”), and the Company agreed to reduce Sobi’s royalty payment obligations under the Sobi Collaboration Agreement by 90%, effective July 1, 2025. The royalty reduction is subject to defined caps tied to Aspaveli’s performance, including an initial cap of 1.45x of the purchase price.

The royalty reduction subject to the cap is calculated as an amount equal to (A) the royalty payments that would have been payable by Sobi under the Sobi Collaboration Agreement with respect to aggregate net sales of Aspaveli outside the United States

during the period beginning on July 1, 2025 and ending on the hard cap achievement date if the 90% reduction not been applied, minus (B) the royalty payments that are payable to the Company with the 90% reduction in effect. At any time on or after October 1, 2030, the Company may elect to pay Sobi a one-time payment amount, which shall be counted in determining if a cap is met. If a cap is met, Sobi’s royalty payment obligations under the Sobi Collaboration Agreement will revert to 100%.

The Company has evaluated the terms of the Royalty Agreement and concluded, in accordance with ASC 606, the Royalty Agreement is a modification to, and should be accounted for as if it were part of, the existing Sobi Collaboration Agreement. Therefore, the effect of the modification on the transaction price, being the addition of the $275.0 million upfront payment, was recognized as an adjustment to revenue on the date of the modification. This amount is reflected in licensing and other revenue on the consolidated statement of operations and comprehensive income/(loss) for the year ended December 31, 2025. The royalty revenues from the sales of Aspaveli will continue to be recorded as licensing and other revenue on the consolidated statement of operations and comprehensive income/(loss) as the sales are made by Sobi outside of the United States.

In January 2026, Sobi received EMA approval of Aspaveli for C3G and primary IC-MPGN. Pursuant to the Royalty Agreement, Sobi owed us an additional $25.0 million, which was paid in February 2026. This $25.0 million will be recorded as licensing and other revenue on the consolidated statement of operations and comprehensive income/(loss) in the first quarter of 2026.

Under the Sobi Collaboration Agreement, as of December 31, 2025, 2024 and 2023, the Company recognized $13.2 million, $18.4 million, and $10.0 million, respectively, of royalty revenue from sales of Aspaveli, which was sold by Sobi outside of the United States.

As of December 31, 2025 and 2024, the Company recognized $10.6 million and $9.9 million, respectively, of contra-research and development expense related to reimbursements from Sobi for certain agreed upon development activities. Additionally, as it relates to the $80.0 million reimbursement commitment from Sobi, the Company recognized $65.0 million as contra-research and development expense between 2020 and 2023, and waived the remaining $15.0 million reimbursement in 2024 in connection with the decision to discontinue the CAD program.

University of Pennsylvania License Agreement

Patent License Agreement with Penn (Non-ophthalmic Fields of Use)

The Company is party to a license agreement with Penn for an exclusive, worldwide license to specified patent rights for the development and commercialization of products in fields of use, as defined therein. The Company is required to make milestone payments aggregating up to $1.7 million, based upon the achievement of development and regulatory approval milestones, and up to $2.5 million, based upon the achievement of annual sales milestones with respect to each of the first two licensed products. The license agreement also requires the Company to pay low single-digit royalties based on net sales of each licensed product, subject to minimum quarterly royalty thresholds. In addition, the Company is obligated to pay a specified portion of income it receives from sublicensees.

From January 2021 through December 2025, the Company has made sublicense payments to Penn totaling $30.5 million. From January 2021 through December 2025, the Company has paid $3.5 million in development and sales milestones.

As of December 31, 2025, 2024 and 2023, the Company has incurred royalty expense of $7.3 million, $6.4 million and $4.8 million, respectively, on sales of EMPAVELI and Aspaveli, which is included in cost of sales on the consolidated statements of operations and comprehensive income/(loss).

Amended and Restated Patent License Agreement with Penn (Ophthalmic Field of Use)

The Company is also party to a license agreement with Penn for an exclusive, worldwide license to specified patent rights. The Company is required to make milestone payments aggregating up to $3.2 million based upon the achievement of specified development and regulatory milestones and up to $5.0 million based upon the achievement of specified annual sales milestones with respect to each licensed product, and to pay low single-digit royalties based on net sales of each licensed product and with minimum quarterly royalty thresholds. In addition, the Company is obligated to pay a specified portion of income it receives from sublicensees.

From April 2023 through December 2025, the Company paid $7.3 million related to regulatory and sales milestones for SYFOVRE.

As of December 31, 2025, 2024 and 2023 respectively, the Company has incurred royalty expense of $19.1 million, $19.8 million and $8.9 million on sales of SYFOVRE, which is included in cost of sales on the consolidated statements of operations and comprehensive income/(loss).

Beam Research Collaboration

In June 2021, the Company entered into an exclusive five-year research collaboration (the “Beam Collaboration Agreement”) with Beam Therapeutics, Inc. (“Beam”) focused on the use of Beam’s proprietary base editing technology to discover new treatments for complement-driven diseases. The Company and Beam agreed to collaborate on up to six research programs focused on C3 and other complement targets in the eye, liver and brain. Under the terms of the Beam Collaboration Agreement, the Company is

responsible for selecting specific genes within the complement system in various organs including the eye, liver and brain (the “Target List”) and providing analytical support while Beam will apply its base editing technology and conduct preclinical research on up to six base editing programs for the Target List. During the first five years of the Beam Collaboration Agreement, Beam is prohibited from developing on its own or with a third-party any base editing therapies associated with the items on the Target List but does not prevent Beam from licensing its intellectual property to a third-party for another purpose outside of the Target List. The Company will have exclusive rights to license each of the six programs and will assume responsibility for subsequent development and commercialization. Beam may elect to enter a 50-50 co-development and U.S. co-commercialization agreement with the Company with respect to any one program licensed under the Beam Collaboration Agreement and upon such election any license agreement in place at that time, would be terminated.

As part of the Beam Collaboration Agreement, the Company made upfront payments of $50.0 million and $25.0 million in 2021 and 2022, respectively. The Company and Beam are each responsible for their own costs during the research collaboration. If and after the opt-in license rights are exercised for each of the up to six programs, Beam will be eligible to receive development, regulatory and sales milestones from the Company, as well as royalty payments on sales. The Beam Collaboration Agreement has an initial term of five years and may be extended up to two years on a per year program-by-program basis.

Further, in August 2025, the Company opted into and entered into a license agreement with Beam to collaborate on the neonatal Fc receptor ("FcRn") in the liver, which triggered an upfront milestone payment of $3.8 million, paid in September 2025. Under this agreement, the Company may pay Beam up to $168.8 million in regulatory and development milestones, up to $215.0 million in sales-based milestones, and may owe low single-digit royalties on annual net sales within the licensed territory.

Accrued Expenses

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Accrued Expenses

6. Accrued Expenses

Accrued expenses consisted of the following as of December 31, 2025 and 2024 (in thousands):


	December 31,
	2025		2024
Accrued research and development	$	16,995	$	22,782
Accrued royalties		7,409		7,147
Accrued payroll liabilities		38,503		40,888
Accrued goods received not invoiced		21,248		638
Product revenue reserves		53,247		45,145
Commercial costs		25,907		20,610
Other		2,740		2,974
Total accrued expenses	$	166,049	$	140,184

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Current assets:
Cash and cash equivalents	$ 466,233	$ 411,290
Accounts receivable	366,221	264,926
Inventory	142,556	81,404
Prepaid and other current assets	38,303	30,012
Restricted cash	1,527	1,322
Total current assets	1,014,840	788,954
Non-current assets:
Right-of-use assets	18,195	16,083
Property and equipment, net	1,708	2,952
Long-term inventory	34,959	75,713
Other assets	5,555	1,349
Total assets	1,075,257	885,051
Current liabilities:
Accounts payable	56,798	38,572
Accrued expenses	166,049	140,184
Convertible senior notes	93,662	0
Current portion of lease liabilities	7,087	6,753
Total current liabilities	323,596	185,509
Long-term liabilities:
Long-term credit facility	361,664	359,489
Convertible senior notes	0	93,341
Lease liabilities	11,947	10,201
Other liabilities	7,903	7,972
Total liabilities	705,110	656,512
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000 shares authorized and zero shares issued and outstanding at December 31, 2025 and 2024	0	0
Common stock, $0.0001 par value; 200,000 shares authorized at December 31, 2025 and 2024; 126,621 and 124,495 shares issued and outstanding at December 31, 2025 and 2024, respectively	12	12
Additional paid-in capital	3,385,216	3,267,201
Accumulated other comprehensive loss	(2,103)	(3,308)
Accumulated deficit	(3,012,978)	(3,035,366)
Total stockholders’ equity	370,147	228,539
Total liabilities and stockholders’ equity	$ 1,075,257	$ 885,051

Income Taxes - Schedule of Income Taxes Paid (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Paid, by Individual Jurisdiction [Line Items]
U.S. Federal			$ (2,500)
U.S. State and Local	$ 1,332	$ 938	694
Foreign	299	711	47
Total	1,631	1,649	(1,759)
Tennessee [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
U.S. State and Local	806	730	94
Pennsylvania [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
U.S. State and Local	266		471
Kentucky [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
U.S. State and Local		540
Massachusetts [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
U.S. State and Local		(284)	206
North Dakota [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
U.S. State and Local			(90)
Other [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
U.S. State and Local	260	(48)	13
Germany [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign	126
United Kingdom [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign		111
Canada [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign		337
Italy [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign		99
Other [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign	$ 173	$ 164	$ 47

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Payables and Accruals [Abstract]
Accrued research and development	$ 16,995	$ 22,782
Accrued royalties	7,409	7,147
Accrued payroll liabilities	38,503	40,888
Accrued goods received not invoiced	21,248	638
Product revenue reserves	53,247	45,145
Commercial costs	25,907	20,610
Other	2,740	2,974
Total accrued expenses	$ 166,049	$ 140,184

Long Term Debt - Summary of Interest Expense Recognized Related to Credit Facility (Detail) - Credit Facility [Member] - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 2,175,000	$ 1,250,000
Contractual interest expense	37,947,000	26,082,000
Total interest expense	$ 40,122,000	$ 27,332,000	$ 0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477314/942-235-S99-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-4

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-Name Accounting Standards Codification
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-Paragraph 3
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+ Details

Equity Incentive Plans - Summary of Assumption Used to Estimate Grant Date Fair Value (Detail)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate, minimum	3.77%	3.94%	3.50%
Risk-free interest rate, maximum	4.42%	4.36%	4.01%
Dividend yield	0.00%	0.00%	0.00%
Volatility, minimum	70.32%	71.91%	68.40%
Volatility, maximum	73.11%	77.01%	71.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected terms (years)	2 years 3 months	3 years 9 months 21 days	3 years 9 months 21 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected terms (years)	6 years 3 months	6 years 29 days	6 years 29 days
Market-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate	4.50%
Dividend yield	0.00%
Volatility	72.20%

Inventory - Schedule Of Inventory Current (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Inventory Disclosure [Abstract]
Raw materials	$ 43,290	$ 54,385
Semi-finished goods	121,207	92,872
Finished goods	13,018	9,860
Total inventories	$ 177,515	$ 157,117

Product Revenues, Accounts Receivable, and Reserves for Product Sales

12 Months Ended

Dec. 31, 2025

Product Revenues Accounts Receivable And Reserves For Product Sales [Abstract]

Product Revenues, Accounts Receivable, and Reserves for Product Sales

3. Product Revenues, Accounts Receivable, and Reserves for Product Sales

The table reflects net product revenue by major source for the following periods (in thousands):


			Year Ended December 31,
	Therapeutic Area	Key Indications	2025		2024		2023
Products:
EMPAVELI	Rare Disease	PNH, C3G (1), IC-MPGN (1)	$	102,449	$	98,091	$	91,033
SYFOVRE	Ophthalmology	GA		586,934		611,863		275,248
Total product revenue, net			$	689,383	$	709,954	$	366,281

(1) The FDA approved EMPAVELI for the treatment of C3G and primary IC-MPGN on July 28, 2025.

The Company’s product sales reserves totaled $58.6 million and $45.1 million as of December 31, 2025 and 2024, respectively.

The following table summarizes activity in each of the product revenue allowance and reserve categories as of December 31, 2025 (in thousands)::


	Fees and patient assistance			Government, Other Rebates, and Chargebacks (1)			Returns			Total
Ending balance at December 31, 2022	$	164		$	1,936		$	251		$	2,351
Provision related to sales in the current year		17,690			26,661			4,698			49,050
Adjustments related to prior period sales		(112	)		(1,223	)		(2,481	)		(3,817	)
Credits and payments made		(12,068	)		(18,476	)		(415	)		(30,960	)
Ending balance at December 31, 2023	$	5,674		$	8,898		$	2,053		$	16,625
Provision related to sales in the current year		46,506			89,094			3,936			139,536
Adjustments related to prior period sales		1,461			(19	)		(96	)		1,346
Credits and payments made		(42,052	)		(66,440	)		(3,870	)		(112,362	)
Ending balance at December 31, 2024	$	11,589		$	31,533		$	2,023		$	45,145
Provision related to sales in the current year		49,594			140,065			5,652			195,311
Adjustments related to prior period sales		298			(13	)		(382	)		(97	)
Credits and payments made		(48,707	)		(128,658	)		(4,380	)		(181,745	)
Ending balance at December 31, 2025	$	12,774		$	42,927		$	2,913		$	58,614


	Percent of Total Gross Product Revenues
	Year Ended December 31,
	2025	2024	2023
Customer A	13%	13%	24%
Customer C	19%	19%	16%
Customer D	58%	59%	54%


	Percent of Product Sales Receivable
	As of December 31,
	2025	2024
Customer C	22%	29%
Customer D	66%	55%

Factoring of accounts receivable and associated fees for the years ended December 31, 2025, and 2024 were as follows (in thousands):


	December 31,			December 31,
	2025			2024
Accounts receivable sold	$	199,447		$	142,698
Less: factoring fees		(2,434	)		(1,700	)
Net cash proceeds	$	197,013		$	140,998

The accounts receivable sold that remained outstanding as of December 31, 2025 and 2024 was zero and $86.1 million, respectively.

Insider Trading Arrangements

3 Months Ended

Dec. 31, 2025

Trading Arrangements, by Individual

Material Terms of Trading Arrangement

The following table describes, for the quarterly period covered by this report, each trading arrangement for the sale or purchase of our securities adopted or terminated by our directors and officers that is either (1) a contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c), or a Rule 10b5-1 trading arrangement, or (2) a “non-Rule 10b5-1 trading arrangement” (as defined in Item 408(c) of Regulation S-K):


Name (Title)	Action Taken (Date of Action)	Type of Trading Arrangement	Nature of Trading Arrangement	Duration of Trading Arrangement	Aggregate Number of Securities
Tim Sullivan Chief Financial Officer and Treasurer	Adoption 12/11/2025	Rule 10b5-1 trading arrangement	Sale	Until 9/30/2026, or such earlier date upon which all transactions are completed or expire without execution	Up to 30,000 shares

Tim Sullivan [Member]

Trading Arrangements, by Individual

Name

Tim SullivanChief

Title

Chief Financial Officer and Treasurer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

12/11/2025

Expiration Date

9/30/2026

Aggregate Available

30,000

Equity Incentive Plans - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning balance	8,048
Shares, Granted	2,919	700	800
Shares, Exercised	(438)
Shares, Forfeited	(1,466)
Shares Outstanding, Ending balance	9,063	8,048
Shares, Options exercisable	5,919
Shares, Expected to vest	3,144
Weighted -Average Exercise Price Per Share Outstanding, Beginning balance	$ 35.36
Weighted -Average Exercise Price Per Share, Granted	20.17
Weighted -Average Exercise Price Per Share, Exercised	12.65
Weighted -Average Exercise Price Per Share, Forfeited	44.07
Weighted -Average Exercise Price Per Share, Outstanding, Ending balance	30.16	$ 35.36
Weighted -Average Exercise Price Per Share, Options exercisable	33.00
Weighted -Average Exercise Price Per Share, Expected to vest	$ 24.82
Weighted - Average Contractual Life, Options exercisable	4 years 1 month 2 days
Weighted - Average Contractual Life, Expected to vest	3 years 10 months 20 days
Aggregate Intrinsic Value, Options exercisable	$ 24,018
Aggregate Intrinsic Value, Expected to vest	$ 14,763

Income Taxes

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Income Taxes

12. Income Taxes

The components of net income/(loss) from continuing operations before provision for income taxes are as follows (in thousands):


	Year Ended December 31,
	2025			2024			2023
United States	$	(120,516	)	$	(22,701	)	$	(48,495	)
Foreign		144,626			(174,015	)		(478,001	)
Total	$	24,110		$	(196,716	)	$	(526,496	)

Provision for income taxes for the years ended December 31, 2025, 2024, and 2023 are as follows (in thousands):


	Year Ended December 31, 2025		Year Ended December 31, 2024		Year Ended December 31, 2023
Current income tax expense:
U.S. Federal	$	—	$	—	$	—
U.S. State and Local		1,550		474		1,869
Foreign		172		688		263
Total current income tax expense		1,722		1,162		2,132
Deferred income tax expense:
U.S. Federal		—		—		—
U.S. State and Local		—		—		—
Foreign		—		—		—
Total deferred income tax expense		—		—		—
Total tax expense	$	1,722	$	1,162	$	2,132

The Company has elected to retrospectively adopt the guidance in ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Taxes Disclosures, or ASU 2023-09. A reconciliation between the U.S. federal statutory tax rate and the Company's effective tax rate, in accordance with the guidance in ASU 2023-09, is summarized as follows (in thousands):


	Year Ended December 31,
	2025						2024						2023

Rate Reconciliation	Amount			Percent			Amount			Percent			Amount			Percent
Net income/(loss) before taxes	$	24,110					$	(196,716	)				$	(526,496	)
US federal statutory income tax rate		5,063			21.0	%		(41,310	)		21.0	%		(110,564	)		21.0	%
Domestic federal reconciling items
Tax credits
Research credits		5,720			23.7	%		(22,100	)		11.2	%		(11,566	)		2.2	%
Nontaxable and nondeductible items
Stock-based compensation		10,938			45.4	%		(8,688	)		4.4	%		(26,881	)		5.1	%
162M		1,634			6.8	%		2,720			(1.4	%)		1,588			(0.3	%)
Other		609			2.5	%		374			(0.2	%)		(1,382	)		0.3	%
Cross-border tax laws
GILTI		638			2.6	%		59,627			(30.3	%)		—			—	%
Valuation allowance		5,770			23.9	%		(32,130	)		16.3	%		46,030			(8.7	%)
Prior year taxes		—			—	%		4,965			(2.5	%)		2,396			(0.5	%)
Domestic state and local income taxes, net of federal benefit		1,550			6.4	%		474			(0.2	%)		1,869			(0.4	%)
Foreign tax effected
Switzerland
Statutory income tax rate differential		(19,725	)		(81.8	%)		20,443			(10.4	%)		62,293			(11.8	%)
Valuation allowance		(11,325	)		(47.0	%)		11,372			(5.8	%)		37,044			(7.0	%)
Other		(394	)		(1.6	%)		798			(0.4	%)		(2	)		—	%
Bermuda
Statutory income tax rate differential		3			—	%		3,150			(1.6	%)		6			—	%
Australia
Statutory income tax rate differential		(434	)		(1.8	%)		(505	)		0.3	%		(561	)		0.1	%
Valuation Allowance		1,503			6.2	%		1,451			(0.7	%)		1,595			(0.3	%)
Other		(57	)		(0.2	%)		231			(0.1	%)		275			(0.1	%)
Other foreign jurisdictions		229			1.0	%		290			(0.2	%)		(8	)		—	%
Total	$	1,722			7.1	%	$	1,162			(0.6	%)	$	2,132			(0.4	%)

The Company’s effective income tax rate for the year ended December 31, 2025 compared to the year ended December 31, 2024 increased primarily as a result of operations in state jurisdictions.

The following table presents the principal components of the Company’s deferred tax assets and liabilities (in thousands):


	December 31,
	2025			2024
Deferred tax assets:
Intangible assets	$	178,715		$	177,244
Research and development capitalization		13,831			21,474
Contribution carryforward		8,782			—
Share-based compensation		43,966			38,494
Net operating loss carryforwards		306,448			312,672
Research and development credits		81,832			81,340
Orphan drug credits		43,129			48,015
Convertible debt		467			1,021
Fixed assets		370			194
Lease liability		3,972			3,026
Accruals		10,966			7,668
Deferred interest expense		4,234			1,974
Inventory reserves		42,051			31,476
UNICAP		(84	)		1,806
Total deferred tax assets		738,679			726,404
Deferred tax liabilities:
Right-of-use asset		(3,863	)		(2,821	)
Total deferred tax liabilities		(3,863	)		(2,821	)
Net deferred tax assets before allowance:		734,816			723,583
Less valuation allowance		(734,816	)		(723,583	)
Net deferred tax assets	$	—		$	—

Management has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets and has determined that it is more likely than not that the Company will not recognize the benefits of its net federal, foreign and state deferred tax assets, and as a result, a valuation allowance of $734.8 million and $723.6 million has been established at December 31, 2025 and 2024, respectively.

On July 4, 2025, the U.S. signed into law the H.R.1 legislation commonly referred to as the OBBBA. The OBBBA contains significant tax provisions, such as permanent extension of certain expiring provisions of the Tax Cuts and Jobs Act and the restoration of favorable tax treatment for certain business provisions. The legislation has multiple effective dates, with certain provisions effective in 2025 and others implemented through 2027. The OBBBA did not result in any material adjustments to the Company’s total income tax provision for the year ended December 31, 2025, and the Company have adjusted our deferred tax balances to reflect the impacts of the OBBBA enactment. However, given the complexity of tax laws, related regulations and interpretations, the Company’s current estimates may require revision as additional information becomes available regarding the application of the OBBBA provisions.

On December 31, 2025, the Company had approximately $427.1 million, $858.7 million and $1,443.6 million of federal, state and foreign net operating loss carryforward, respectively. On December 31, 2024, the Company had approximately $422.5 million, $621.8 million and $1,515.7 million of federal, state and foreign net operating loss carryforward, respectively. The Company also had federal and state research and development tax credit carryforwards, $102.1 million and $27.9 million, respectively as of December 31, 2025. Federal net operating loss carryforward in the amount of $425.6 million may be carried forward indefinitely. The remaining federal and state net operating loss, research and development tax credit carryforwards began to expire in 2025. The Company’s foreign net operating loss carryforwards will begin to expire in 2027.

Under the provisions of the Internal Revenue Code (“IRC”), the net operating loss (“NOL”), and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the IRC, respectively, as well as similar state provisions. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. The Company experienced a Section 382 ownership change in September 2015, which imposes annual limitations on the Company's use of pre-change net operating loss carryforwards and other pre-change tax attributes.

The Company does not have any unrecognized tax benefits during any periods presented and does not expect this to significantly change in the next twelve months. There were no interest and penalties recorded in the statement of operations during any period and no amounts accrued for interest and penalties on December 31, 2025 or 2024.

The following table presents income taxes paid (net of refunds received), in accordance with the guidance in ASU 2023-09, is summarized as follows (in thousands):


	Year Ended December 31,
	2025		2024			2023
U.S. Federal	$	—	$	—		$	(2,500	)
U.S. State and Local
Tennessee		806		730			94
Pennsylvania		266	*				471
Kentucky	*			540		*
Massachusetts	*			(284	)		206
North Dakota	*		*				(90	)
Other		260		(48	)		13
Total U.S. State and Local	$	1,332	$	938		$	694
Foreign
Germany		126	*			*
United Kingdom	*			111		*
Canada	*			337		*
Italy	*			99		*
Other		173		164			47
Total Foreign		299		711			47
Total	$	1,631	$	1,649		$	(1,759	)

* The amount of income taxes paid during the year does not meet the 5% disaggregation threshold.

The Company and its subsidiaries file income tax returns in the United States, as well as various state and foreign jurisdictions. Generally, tax years 2022 through 2024 remain open and subject to examination by the major taxing jurisdictions to which the Company is subject. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service, or state or foreign tax authorities, to the extent utilized in a future period.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477617/942-740-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478822/944-740-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 231
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-231

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12C

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12B

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477891/740-270-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479360/740-10-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
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-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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-Topic 740
-Name Accounting Standards Codification
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org/1943274/2147482685/740-10-50-14

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Topic 740
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482603/740-30-50-2

+ Details

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Customer Accounted for 10% of More of Gross Product Revenues and Accounts Receivable (Detail) - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Gross Product Revenues [Member] \| Customer A [Member]
Revenue, Major Customer [Line Items]
Concentration risk	13.00%	13.00%	24.00%
Gross Product Revenues [Member] \| Customer C [Member]
Revenue, Major Customer [Line Items]
Concentration risk	19.00%	19.00%	16.00%
Gross Product Revenues [Member] \| Customer D [Member]
Revenue, Major Customer [Line Items]
Concentration risk	58.00%	59.00%	54.00%
Product Sales Receivable [Member] \| Customer C [Member]
Revenue, Major Customer [Line Items]
Concentration risk	22.00%	29.00%
Product Sales Receivable [Member] \| Customer D [Member]
Revenue, Major Customer [Line Items]
Concentration risk	66.00%	55.00%

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References + Details

Inventory - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Inventory Disclosure [Abstract]
Reserve for excess and obsolete inventory	$ 20.5	$ 19.0

Commitments and Contingencies - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2026	Dec. 31, 2025	Dec. 31, 2024
Commitments And Contingencies [Line Items]
Accrued expenses		$ 166,049,000	$ 140,184,000
Other liabilities		7,903,000	$ 7,972,000
Incurred any cost to defend lawsuits or settle claims		0
Bachem Americas, Inc [Member]
Commitments And Contingencies [Line Items]
Non-cancellable purchase commitments		$ 69,100,000
Non-cancellable purchase commitment period		3 years
Accrued expenses		$ 6,400,000
Other liabilities		6,400,000
Other non-cancellable purchase commitments		$ 6,700,000
Vehicles [Member]
Commitments And Contingencies [Line Items]
Operating lease, term of contract		36 months
Forecast [Member]
Commitments And Contingencies [Line Items]
Non-cancellable purchase commitments	$ 6,400,000

Cybersecurity Risk Management, Strategy, and Governance	12 Months Ended
Cybersecurity Risk Management, Strategy, and Governance	Dec. 31, 2025
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	Item 1C. Cybersecurity. We have certain processes for assessing, identifying and managing cybersecurity risks, which are built into our information technology function and are designed to help protect our information assets and operations from internal and external cyber threats and employee, health care professionals, or HCPs, and patient information from unauthorized access or attack, as well as secure our networks and systems. Such processes include physical, procedural and technical safeguards, response plans, regular tests on our systems, incident simulations and routine review of our policies and procedures to identify risks and improve our practices. We engage certain external parties, including consultants, independent privacy assessors, and computer security firms to enhance our cybersecurity oversight. We consider the internal risk oversight programs of third-party service providers before engaging them in order to help protect us from any related vulnerabilities. We do not believe that there are currently any known risks from cybersecurity threats that are reasonably likely to materially affect us or our business strategy, results of operations or financial condition. The Audit Committee of the Board of Directors provides direct oversight over cybersecurity risk. The Audit Committee receives quarterly updates from management regarding cybersecurity matters, and is notified between such updates regarding significant new cybersecurity threats or incidents. Our Head of Information Technology leads the operational oversight of company-wide cybersecurity strategy, policy, standards and processes and works across relevant departments to assess and help prepare us and our employees and third-party service providers to address cybersecurity risks. The Head of Information Technology has over 12 years of experience within the life sciences industry building and maintaining cybersecurity programs. Our cybersecurity function, led by the Head of Information Technology, brings security credentials and expertise, with broad global cybersecurity and compliance experience in life science, healthcare, and federal government. In addition to our cybersecurity team, a managed security service provider provides us with additional coverage to monitor, detect and respond to threats and vulnerabilities. In an effort to deter and detect cyber threats, we provide all employees, including part-time and temporary employees, with cybersecurity information and training, which covers timely and relevant topics, including social engineering, phishing, password protection, confidential data protection, asset use and mobile security, and educates employees on the importance of reporting all incidents immediately. Our third-party risk management program is integrated with global sourcing and procurement, and requires vendor risk assessments, incident reporting, and data protection controls. We also use technology-based tools to mitigate cybersecurity risks and to bolster our employee-based cybersecurity programs.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	Our third-party risk management program is integrated with global sourcing and procurement, and requires vendor risk assessments, incident reporting, and data protection controls. We also use technology-based tools to mitigate cybersecurity risks and to bolster our employee-based cybersecurity programs.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	The Audit Committee of the Board of Directors provides direct oversight over cybersecurity risk. The Audit Committee receives quarterly updates from management regarding cybersecurity matters, and is notified between such updates regarding significant new cybersecurity threats or incidents.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	The Audit Committee receives quarterly updates from management regarding cybersecurity matters, and is notified between such updates regarding significant new cybersecurity threats or incidents.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	The Audit Committee receives quarterly updates from management regarding cybersecurity matters
Cybersecurity Risk Role of Management [Text Block]	Our Head of Information Technology leads the operational oversight of company-wide cybersecurity strategy, policy, standards and processes and works across relevant departments to assess and help prepare us and our employees and third-party service providers to address cybersecurity risks. The Head of Information Technology has over 12 years of experience within the life sciences industry building and maintaining cybersecurity programs. Our cybersecurity function, led by the Head of Information Technology, brings security credentials and expertise, with broad global cybersecurity and compliance experience in life science, healthcare, and federal government. In addition to our cybersecurity team, a managed security service provider provides us with additional coverage to monitor, detect and respond to threats and vulnerabilities.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	Our Head of Information Technology leads the operational oversight of company-wide cybersecurity strategy, policy, standards and processes and works across relevant departments to assess and help prepare us and our employees and third-party service providers to address cybersecurity risks.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	The Head of Information Technology has over 12 years of experience within the life sciences industry building and maintaining cybersecurity programs. Our cybersecurity function, led by the Head of Information Technology, brings security credentials and expertise, with broad global cybersecurity and compliance experience in life science, healthcare, and federal government.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	In addition to our cybersecurity team, a managed security service provider provides us with additional coverage to monitor, detect and respond to threats and vulnerabilities.

Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2025

Debt Disclosure [Abstract]

Schedule of Outstanding Balance of Convertible Notes

The outstanding balance of the Convertible Notes as of December 31, 2025 and 2024 consisted of the following (in thousands):


	December 31,
	2025			2024
Principal	$	93,897		$	93,897
Less: debt discount and issuance costs, net		(235	)		(556	)
Net carrying amount	$	93,662		$	93,341

Schedule of Interest Expense Recognized Related to Convertible Notes

The following table sets forth total interest expense recognized related to the Convertible Notes during the years ended December 31, 2025, 2024 and 2023 (in thousands):


	Year Ended December 31,
	2025		2024		2023
Amortization of debt issuance costs	$	321	$	309	$	297
Contractual interest expense		3,286		3,286		3,286
Total interest expense	$	3,607	$	3,595	$	3,583

Summary of Credit Facility

The outstanding balance of the Credit Facility as of December 31, 2025 and 2024 consisted of the following (in thousands):


	December 31,			December 31,
	2025			2024
Principal	$	375,000		$	375,000
Less: debt discount and issuance costs		(13,336	)		(15,511	)
Net carrying amount	$	361,664		$	359,489

Summary of Interest Expense Recognized Related to Credit Facility

The following table sets forth total interest expense recognized related to the Credit Facility as of December 31, 2025 and 2024 (in thousands):


	December 31,
	2025		2024
Amortization of debt issuance costs	$	2,175	$	1,250
Contractual interest expense		37,947		26,082
Total interest expense	$	40,122	$	27,332

Fair Value Measurements - Schedule of Financial Instruments and the Related Fair Value Hierarchy of the Valuation Techniques Utilized (Detail) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	$ 349,615	$ 276,868
Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	349,615	276,868
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	349,615	276,868
Level 1 [Member] \| Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	$ 349,615	$ 276,868

Leases - Schedule of Additional Information Related to Operating Lease (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Leases [Abstract]
Right-of-use assets	$ 18,195	$ 16,083
Operating lease liabilities	$ 19,034	$ 16,954
Weighted average remaining term in years	3 years 3 months 21 days	2 years 8 months 23 days
Weighted average discount rate used to measure outstanding lease liabilities	6.52%	6.20%

Employee Retirement Plans

12 Months Ended

Dec. 31, 2025

Retirement Benefits [Abstract]

Employee Retirement Plans

11. Employee Retirement Plans

The Company adopted an employee profit-sharing plan (the “401(k) Plan”), qualified under Section 401(k) of the Internal Revenue Code (the “IRC”). All of the Company’s full-time employees who have attained the age of 21 are eligible to participate in the 401(k) Plan immediately upon employment. Pursuant to the 401(k) Plan, employees may elect to reduce their current compensation by up to the statutorily prescribed annual limit and have the amount of the reduction contributed to the 401(k) Plan. For the years ended December 31, 2025, 2024 and 2023, the Company recorded $5.7 million, $5.1 million, and $5.7 million respectively, for employer contributions made to the 401(k) Plan.

The Company maintains a pension plan covering employees of its Swiss subsidiary, Apellis International GmbH (the “Swiss Plan”). The Swiss Plan is a legally-mandated retirement fund that provides employees with a minimum benefit. Employer and employee contributions are made to the Swiss Plan based on various percentages of salary and wages that vary according to employee age and other factors. As is customary with Swiss pension plans, the assets of the Swiss Plan are invested in a collective fund, which are held and invested by a Swiss insurance company. The investment strategy of the Swiss Plan is managed by an independent asset manager with the objective of achieving a consistent long-term return which will provide sufficient funding for future pension obligations while limiting risk.

As of December 31, 2025, the Swiss Plan was underfunded by $0.2 million as the fair value of the plan assets of $11.3 million was less than the projected benefit obligation of $11.5 million. The accumulated benefit obligation at December 31, 2025 was $0.1 million. The Company’s net periodic benefit cost for the year ended December 31, 2025 was $0.7 million. The contributions to the Swiss Plan for the year ended December 31, 2025 were not material.

As of December 31, 2024, the Swiss Plan was underfunded by $1.6 million as the fair value of the plan assets of $16.7 million was less than the projected benefit obligation of $18.3 million. The accumulated benefit obligation at December 31, 2024 was $0.6 million. The Company’s net periodic benefit cost for the year ended December 31, 2024 was $1.2 million. The contributions to the Swiss Plan for the year ended December 31, 2024 were not material.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480266/715-60-50-3

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480126/715-20-S99-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480794/715-70-50-1

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480482/715-20-55-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/715/tableOfContent

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

+ Details

Leases - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Lessee Lease Description [Line Items]
Operating lease cost	$ 10.5	$ 10.2	$ 7.0

Nature of Organization and Operations - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Feb. 22, 2023	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Nature Of Organization And Operations [Line Items]
Accumulated deficit		$ (3,012,978)	$ (3,035,366)
Cash and cash equivalents		$ 466,233	$ 411,290	$ 351,185
Follow-on Public Offerings [Member]
Nature Of Organization And Operations [Line Items]
Issuance of common stock and pre-funded warrants in common stock offering, shares	4,007,936
Pre funded warrant price	$ 62.9999
Common stock pre funded warrants per warrant	0.0001
Price of common stock	$ 63
Proceeds from follow-on public offering after deducting underwriting discounts and commissions	$ 384,400
Underwriting discounts and commissions	18,800
Offering Costs	$ 300
Common Stock [Member]
Nature Of Organization And Operations [Line Items]
Issuance of common stock and pre-funded warrants in common stock offering, shares		80,956		4,008,000
Shares issued upon exercise of pre-funded warrants			2,299,991
Common Stock [Member] \| Follow-on Public Offerings [Member]
Nature Of Organization And Operations [Line Items]
Issuance of common stock and pre-funded warrants in common stock offering, shares	2,380,956
Common Stock [Member] \| Over Allotment Option [Member]
Nature Of Organization And Operations [Line Items]
Issuance of common stock and pre-funded warrants in common stock offering, shares	833,333

Fair Value Measurements - Additional Information (Detail) - Level 1 [Member] - Convertible Senior Notes [Member] - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible notes	$ 97.5	$ 102.3
Convertible notes, interest rate	3.50%	3.50%

Income Taxes - Schedule of Reconciliation Between U.S. Federal Statutory Rate and Effective Tax rate, Amount (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Effective Income Tax Rate Reconciliation [Line Items]
Net income/(loss) before taxes	$ 24,110	$ (196,716)	$ (526,496)
US federal statutory income tax rate, Amount	5,063	(41,310)	(110,564)
Research credits, Amount	5,720	(22,100)	(11,566)
Nontaxable and nondeductible items
Stock-based compensation, Amount	10,938	(8,688)	(26,881)
162M, Amount	1,634	2,720	1,588
Other, Amount	609	374	(1,382)
Cross-border tax laws
GILTI, Amount	638	59,627
Valuation allowance, Amount	5,770	(32,130)	46,030
Prior year taxes, Amount		4,965	2,396
Domestic state and local income taxes, net of federal benefit, Amount	1,550	474	1,869
Total tax expense	1,722	1,162	2,132
Bermuda [Member]
Cross-border tax laws
Statutory income tax rate differential, Amount	3	3,150	6
Switzerland [Member]
Cross-border tax laws
Valuation allowance, Amount	(11,325)	11,372	37,044
Statutory income tax rate differential, Amount	(19,725)	20,443	62,293
Other, Amount	(394)	798	(2)
Australia [Member]
Cross-border tax laws
Valuation allowance, Amount	1,503	1,451	1,595
Statutory income tax rate differential, Amount	(434)	(505)	(561)
Other, Amount	(57)	231	275
Other Foreign Jurisdictions [Member]
Cross-border tax laws
Statutory income tax rate differential, Amount	$ 229	$ 290	$ (8)

Net Income/(Loss) per Common Share (Tables)

12 Months Ended

Dec. 31, 2025

Earnings Per Share [Abstract]

Summary of Basic and Diluted Net Income/(Loss) per Common Share

The following table presents the calculation of basic and diluted net income/(loss) per common share (amounts in thousands, except per share amounts):


	Year Ended December 31,
	2025		2024			2023
Basic net income/(loss) per share
Numerator:
Net income/(loss)	$	22,388	$	(197,878	)	$	(528,628	)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic		126,145		123,905			118,678
Net income/(loss) per common share - basic	$	0.18	$	(1.60	)	$	(4.45	)

Diluted net income/(loss) per share
Numerator:
Net income/(loss)	$	22,388	$	(197,878	)	$	(528,628	)
Adjustment - Interest expense on Convertible Notes		3,607		—			—
Adjusted net income/(loss)	$	25,995	$	(197,878	)	$	(528,628	)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic		126,145		123,905			118,678
Convertible notes		2,379		—			—
Stock options to purchase common stock		967		—			—
Unvested restricted stock units		346		—			—
Shares expected to be purchased under employee stock purchase plan		18		—			—
Weighted-average number of common shares used in net income/(loss) per common share - diluted		129,855		123,905			118,678
Net income/(loss) per common share - diluted	$	0.20	$	(1.60	)	$	(4.45	)

Summary of Potential Common Shares that were Excluded from Calculation of Diluted Net Income/(Loss) Per Share Due to Anti-Dilutive Effect


	Year Ended December 31,
	2025		2024		2023
Convertible notes		—		2,379		2,379
Stock options to purchase common stock		6,506		8,048		8,664
Unvested restricted stock units		3,483		3,962		4,301
Total		9,989		14,389		15,344

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Taxes [Line Items]
Deferred tax assets, valuation allowance	$ 734,816,000	$ 723,583,000
Gross deferred tax assets before allowance	738,679,000	726,404,000
Net deferred tax assets before allowance	734,816,000	723,583,000
Global intangible low-taxed income	$ (638,000)	(59,627,000)
Net operating loss carryforward period	3 years
Interest and penalties	$ 0	0
Accrued for interest and penalties	$ 0	0
Income tax examination description	Generally, tax years 2022 through 2024 remain open and subject to examination by the major taxing jurisdictions to which the Company is subject.
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 427,100,000	422,500,000
Research and development tax credit carryforwards	102,100,000
Net operating loss carryforward indefinitely	$ 425,600,000
Net operating loss carryforward expiration year	2025
Research and development tax credit carryforward expiration year	2025
State [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 858,700,000	621,800,000
Research and development tax credit carryforwards	$ 27,900,000
Net operating loss carryforward expiration year	2025
Research and development tax credit carryforward expiration year	2025
Foreign [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 1,443,600,000	$ 1,515,700,000
Research and development tax credit carryforward expiration year	2027

Equity Incentive Plans - Summary of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense included in expenses	$ 104,003	$ 114,128	$ 105,945
Capitalized share-based compensation expense to inventory	5,128
Total share-based compensation	109,131	114,128	105,945
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense included in expenses	40,105	41,267	45,644
Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense included in expenses	$ 63,898	$ 72,861	$ 60,301

Long-term Debt - Schedule of Interest Expense Recognized Related to Convertible Notes (Detail) - Convertible Senior Notes Due 2026 [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 321	$ 309	$ 297
Contractual interest expense	3,286	3,286	3,286
Total interest expense	$ 3,607	$ 3,595	$ 3,583

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 7: http://www.xbrl.org/2003/role/exampleRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/exampleRef
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Reference 10: http://www.xbrl.org/2003/role/exampleRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/exampleRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 30: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 31: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Components of Net Income (Loss) From Continuing Operation Before Provision for Income Taxes

The components of net income/(loss) from continuing operations before provision for income taxes are as follows (in thousands):


	Year Ended December 31,
	2025			2024			2023
United States	$	(120,516	)	$	(22,701	)	$	(48,495	)
Foreign		144,626			(174,015	)		(478,001	)
Total	$	24,110		$	(196,716	)	$	(526,496	)

Schedule of Provision for Income Tax Expense

Provision for income taxes for the years ended December 31, 2025, 2024, and 2023 are as follows (in thousands):


	Year Ended December 31, 2025		Year Ended December 31, 2024		Year Ended December 31, 2023
Current income tax expense:
U.S. Federal	$	—	$	—	$	—
U.S. State and Local		1,550		474		1,869
Foreign		172		688		263
Total current income tax expense		1,722		1,162		2,132
Deferred income tax expense:
U.S. Federal		—		—		—
U.S. State and Local		—		—		—
Foreign		—		—		—
Total deferred income tax expense		—		—		—
Total tax expense	$	1,722	$	1,162	$	2,132

Schedule of Reconciliation Between U.S. Federal Statutory Rate and Effective Tax rate

A reconciliation between the U.S. federal statutory tax rate and the Company's effective tax rate, in accordance with the guidance in ASU 2023-09, is summarized as follows (in thousands):


	Year Ended December 31,
	2025						2024						2023

Rate Reconciliation	Amount			Percent			Amount			Percent			Amount			Percent
Net income/(loss) before taxes	$	24,110					$	(196,716	)				$	(526,496	)
US federal statutory income tax rate		5,063			21.0	%		(41,310	)		21.0	%		(110,564	)		21.0	%
Domestic federal reconciling items
Tax credits
Research credits		5,720			23.7	%		(22,100	)		11.2	%		(11,566	)		2.2	%
Nontaxable and nondeductible items
Stock-based compensation		10,938			45.4	%		(8,688	)		4.4	%		(26,881	)		5.1	%
162M		1,634			6.8	%		2,720			(1.4	%)		1,588			(0.3	%)
Other		609			2.5	%		374			(0.2	%)		(1,382	)		0.3	%
Cross-border tax laws
GILTI		638			2.6	%		59,627			(30.3	%)		—			—	%
Valuation allowance		5,770			23.9	%		(32,130	)		16.3	%		46,030			(8.7	%)
Prior year taxes		—			—	%		4,965			(2.5	%)		2,396			(0.5	%)
Domestic state and local income taxes, net of federal benefit		1,550			6.4	%		474			(0.2	%)		1,869			(0.4	%)
Foreign tax effected
Switzerland
Statutory income tax rate differential		(19,725	)		(81.8	%)		20,443			(10.4	%)		62,293			(11.8	%)
Valuation allowance		(11,325	)		(47.0	%)		11,372			(5.8	%)		37,044			(7.0	%)
Other		(394	)		(1.6	%)		798			(0.4	%)		(2	)		—	%
Bermuda
Statutory income tax rate differential		3			—	%		3,150			(1.6	%)		6			—	%
Australia
Statutory income tax rate differential		(434	)		(1.8	%)		(505	)		0.3	%		(561	)		0.1	%
Valuation Allowance		1,503			6.2	%		1,451			(0.7	%)		1,595			(0.3	%)
Other		(57	)		(0.2	%)		231			(0.1	%)		275			(0.1	%)
Other foreign jurisdictions		229			1.0	%		290			(0.2	%)		(8	)		—	%
Total	$	1,722			7.1	%	$	1,162			(0.6	%)	$	2,132			(0.4	%)

Schedule of Deferred Tax Assets and Liabilities

The following table presents the principal components of the Company’s deferred tax assets and liabilities (in thousands):


	December 31,
	2025			2024
Deferred tax assets:
Intangible assets	$	178,715		$	177,244
Research and development capitalization		13,831			21,474
Contribution carryforward		8,782			—
Share-based compensation		43,966			38,494
Net operating loss carryforwards		306,448			312,672
Research and development credits		81,832			81,340
Orphan drug credits		43,129			48,015
Convertible debt		467			1,021
Fixed assets		370			194
Lease liability		3,972			3,026
Accruals		10,966			7,668
Deferred interest expense		4,234			1,974
Inventory reserves		42,051			31,476
UNICAP		(84	)		1,806
Total deferred tax assets		738,679			726,404
Deferred tax liabilities:
Right-of-use asset		(3,863	)		(2,821	)
Total deferred tax liabilities		(3,863	)		(2,821	)
Net deferred tax assets before allowance:		734,816			723,583
Less valuation allowance		(734,816	)		(723,583	)
Net deferred tax assets	$	—		$	—

Schedule of Income Tax Paid Net

The following table presents income taxes paid (net of refunds received), in accordance with the guidance in ASU 2023-09, is summarized as follows (in thousands):


	Year Ended December 31,
	2025		2024			2023
U.S. Federal	$	—	$	—		$	(2,500	)
U.S. State and Local
Tennessee		806		730			94
Pennsylvania		266	*				471
Kentucky	*			540		*
Massachusetts	*			(284	)		206
North Dakota	*		*				(90	)
Other		260		(48	)		13
Total U.S. State and Local	$	1,332	$	938		$	694
Foreign
Germany		126	*			*
United Kingdom	*			111		*
Canada	*			337		*
Italy	*			99		*
Other		173		164			47
Total Foreign		299		711			47
Total	$	1,631	$	1,649		$	(1,759	)

* The amount of income taxes paid during the year does not meet the 5% disaggregation threshold.

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Factoring of Accounts Receivable and Associated Fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Revenue, Major Customer [Line Items]
Accounts receivable sold	$ 199,447	$ 142,698
Less: factoring fees	(2,434)	(1,700)
Net cash proceeds	$ 197,013	$ 140,998