0001193125-25-257374 | 10-Q | XBRL Viewer | Apellis Pharmaceuticals INC

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2025

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

The following table presents the fair value of financial instruments recorded originally at amortized cost or fair value and are not remeasured on a recurring basis (in thousands):


		September 30, 2025
Balance Sheet Classification	Type of Instrument	Level 1		Level 2		Level 3		Total
Financial Assets:
Cash and cash equivalents:	Money market funds	$	215,630	$	—	$	—	$	215,630
Total Financial Assets		$	215,630	$	—	$	—	$	215,630

		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

9 Months Ended

Sep. 30, 2025

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

Product Revenues, Accounts Receivable, and Reserves for Product Sales

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


			Three Months Ended September 30,				Nine Months Ended September 30,
	Therapeutic Area	Key Indications	2025		2024		2025		2024
Products:
EMPAVELI	Rare Disease	PNH, C3G (1), IC-MPGN (1)	$	26,827	$	24,611	$	67,315	$	74,733
SYFOVRE	Ophthalmology	GA		150,928		151,960		431,727		444,049
Total Product revenue, net			$	177,755	$	176,571	$	499,042	$	518,782

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

The Company’s accounts receivable balance of $345.5 million as of September 30, 2025 and $264.9 million as of December 31, 2024, consisted of EMPAVELI and SYFOVRE product sales receivable. The Company does not have a reserve related to expected credit losses against its accounts receivable balance and expects to collect its accounts receivable in the ordinary course of business.

The Company’s product sales reserves totaled $47.4 million and $45.1 million as of September 30, 2025 and December 31, 2024, respectively. These amounts are included in accrued expenses on the Company’s unaudited condensed consolidated balance sheets.

The following table summarizes activity in each of the product revenue allowance and reserve categories for the three and nine months ended September 30, 2025 (in thousands):


	Fees and patient assistance			Government and other rebates			Returns			Total
Ending balance at December 31, 2024	$	11,589		$	31,533		$	2,023		$	45,145
Provision related to sales in the current period		10,277			24,139			976			35,392
Adjustments related to prior period sales		439			(13	)		(382	)		44
Credits and payments made		(13,084	)		(28,467	)		(126	)		(41,677	)
Ending balance at March 31, 2025	$	9,221		$	27,192		$	2,491		$	38,904
Provision related to sales in the current period		12,138			30,823			1,083			44,044
Adjustments related to prior period sales		(66	)		185			852			971
Credits and payments made		(10,833	)		(27,623	)		(941	)		(39,397	)
Ending balance at June 30, 2025	$	10,460		$	30,577		$	3,485		$	44,522
Provision related to sales in the current period		12,695			38,426			1,152			52,273
Adjustments related to prior period sales		366			(12	)		(211	)		143
Credits and payments made		(12,436	)		(34,730	)		(2,324	)		(49,490	)
Ending balance at September 30, 2025	$	11,085		$	34,261		$	2,102		$	47,448

The following table summarizes activity in each of the product revenue allowance and reserve categories for the three and nine months ended September 30, 2024 (in thousands):


	Fees and patient assistance			Government and other rebates			Returns			Total
Ending balance at December 31, 2023	$	5,674		$	8,898		$	2,053		$	16,625
Provision related to sales in the current period		9,575			13,125			1,355			24,055
Adjustments related to prior period sales		146			(19	)		(96	)		31
Credits and payments made		(9,724	)		(9,906	)		(1,859	)		(21,489	)
Ending balance at March 31, 2024	$	5,671		$	12,098		$	1,453		$	19,222
Provision related to sales in the current period		10,025			17,777			1,039			28,841
Adjustments related to prior period sales		(131	)		354			(983	)		(760	)
Credits and payments made		(9,635	)		(14,640	)		(326	)		(24,601	)
Ending balance at June 30, 2024	$	5,930		$	15,589		$	1,183		$	22,702
Provision related to sales in the current period		11,455			25,364			1,380			38,199
Adjustments related to prior period sales		2,332			420			—			2,752
Credits and payments made		(12,078	)		(17,695	)		(979	)		(30,752	)
Ending balance at September 30, 2024	$	7,639		$	23,678		$	1,584		$	32,901

Significant customers - Gross product revenues and product sales receivable from the Company's customers who individually accounted for 10% or 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
	Three Months Ended September 30,		Nine Months Ended September 30,
	2025	2024	2025	2024
Customer A	13%	12%	12%	13%
Customer C	21%	17%	19%	18%
Customer D	58%	61%	59%	59%


	Percent of Product Sales Receivable
	As of September 30,
	2025	2024
Customer A	4%	3%
Customer C	21%	24%
Customer D	67%	61%

Factoring of accounts receivable and associated fees for the three and nine months ended September 30, 2025 and 2024 were as follows (in thousands):


	Three Months Ended September 30,					Nine Months Ended September 30,
	2025		2024			2025			2024
Accounts receivable sold	$	—	$	56,590		$	199,448		$	56,590
Less: factoring fees		—		(672	)		(2,433	)		(672	)
Net cash proceeds	$	—	$	55,918		$	197,015		$	55,918

Accounts receivable sold that remained outstanding as of September 30, 2025 and December 31, 2024 totaled zero and $86.1 million, respectively.

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2025	Oct. 23, 2025
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2025
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q3
Entity Registrant Name	APELLIS PHARMACEUTICALS, INC.
Entity Central Index Key	0001492422
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
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 Common Stock, Shares Outstanding		126,525,218
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Security 12b Title	Common Stock, $0.0001 par value per share
Trading Symbol	APLS
Security Exchange Name	NASDAQ

Long-term Debt - Schedule of Outstanding Balance of Convertible Notes (Detail) - Convertible Senior Notes Due 2026 [Member] - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Principal	$ 93,897	$ 93,897
Less: debt discount and issuance costs, net	(316)	(556)
Net carrying amount	$ 93,581	$ 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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- 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.

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+ Details

Long-term Debt - Additional Information (Detail)				1 Months Ended			9 Months Ended
Long-term Debt - Additional Information (Detail)	Feb. 27, 2024 USD ($)	May 12, 2020 USD ($)	Sep. 16, 2019 USD ($)	Jul. 31, 2022 shares	Jul. 31, 2021 USD ($) shares	Jan. 31, 2021 USD ($) shares	Sep. 30, 2025 USD ($) Days $ / shares	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 semiannually in arrears on March 15 and September 15 of each year, beginning on March 15, 2020.
Debt instrument, frequency of periodic payment							semiannually
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 delivers 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] \| 2019 Convertible Notes [Member] \| Exchange Agreements [Member]
Debt Instrument [Line Items]
Aggregate principal amount converted						$ 126,100,000
Convertible Senior Notes Due 2026 [Member] \| 2019 Convertible Notes [Member] \| Common Stock [Member] \| Exchange Agreements [Member]
Debt Instrument [Line Items]
Aggregate principal amount converted into shares \| shares						3,906,869
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]
Aggregate principal amount converted					$ 98,100,000
Convertible notes held in treasury							$ 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				3,027,018	5,992,217
Convertible Senior Notes Due 2026 [Member] \| 2019 and 2020 Convertible Notes [Member] \| Exchange Agreements [Member]
Debt Instrument [Line Items]
Aggregate principal amount converted					$ 201,100,000
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

Prepaid and Other Current Assets

9 Months Ended

Sep. 30, 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 September 30, 2025 and December 31, 2024 (in thousands):


	September 30,		December 31,
	2025		2024
Down payments for inventory	$	970	$	1,080
Prepaid research and development		20,156		7,780
Other prepaid expenses		10,434		9,508
Total prepaid assets	$	31,560	$	18,368


	September 30,		December 31,
	2025		2024
Royalties receivable	$	6,534	$	4,525
Receivable from collaboration agreement		2,563		2,272
Deposits and other current assets		1,061		4,847
Total other current assets	$	10,158	$	11,644

Fair Value Measurements

9 Months Ended

Sep. 30, 2025

Fair Value Disclosures [Abstract]

Fair Value Measurements

8. Fair Value Measurements

The following table presents the fair value of financial instruments recorded originally at amortized cost or fair value and are not remeasured on a recurring basis (in thousands):


		September 30, 2025
Balance Sheet Classification	Type of Instrument	Level 1		Level 2		Level 3		Total
Financial Assets:
Cash and cash equivalents:	Money market funds	$	215,630	$	—	$	—	$	215,630
Total Financial Assets		$	215,630	$	—	$	—	$	215,630

		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 Company’s Convertible Notes are financial instruments that are reported in the condensed consolidated financial statements at historical cost. The Convertible Notes are Level 1 within the fair value level hierarchy as of September 30, 2025 and December 31, 2024. The fair value of the Convertible Notes was $94.0 million as of September 30, 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 September 30, 2025 and December 31, 2024.

The Company believes that the carrying amounts of remaining financial assets and liabilities, which include other current assets, accounts payable, and accrued expenses, approximates their fair values due to their short-term nature.

- 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
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
-SubTopic 820
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Basis of Presentation and Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 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 unaudited condensed 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 accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted and, accordingly, the condensed consolidated balance sheet as of December 31, 2024 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair presentation of the Company’s financial information. The results of operations for the three and nine months ended September 30, 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2025 or for any other interim period or for any other future year.

The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2024 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 28, 2025 (the “2024 Form 10-K”).

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 as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: accrued research and development expenses, reserves for variable consideration, share-based compensation expense and reserves for excess or obsolete inventories.

Summary of Significant Accounting Policies

Reference is made to Note 2 Summary of Significant Accounting Policies in our 2024 Form 10-K for a detailed description of significant accounting policies. There have been no significant changes to our accounting policies as disclosed in our 2024 Form 10-K.

Recent Accounting Pronouncements issued not yet adopted

In September 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“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 condensed 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 condensed 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, and subsequent amendments with ASU 2025-01, 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 statement. 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.

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 requires entities to provide additional information in the rate reconciliation and additional disaggregated disclosures about income taxes paid. This guidance requires public entities to disclose in their rate reconciliation table additional categories of information about federal, state, and foreign income taxes and to provide more details about the reconciling items in some categories if the items meet a quantitative threshold. The guidance is effective for annual periods beginning after December 15, 2024. The Company is currently evaluating the impact the adoption of this guidance will have on its disclosures.

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

9 Months Ended

Sep. 30, 2025

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

Schedule of Disaggregation of Product Revenue by Major Source

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


			Three Months Ended September 30,				Nine Months Ended September 30,
	Therapeutic Area	Key Indications	2025		2024		2025		2024
Products:
EMPAVELI	Rare Disease	PNH, C3G (1), IC-MPGN (1)	$	26,827	$	24,611	$	67,315	$	74,733
SYFOVRE	Ophthalmology	GA		150,928		151,960		431,727		444,049
Total Product revenue, net			$	177,755	$	176,571	$	499,042	$	518,782

(1) The FDA approved EMPAVELI for the treatment of C3G and 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 for the three and nine months ended September 30, 2025 (in thousands):


	Fees and patient assistance			Government and other rebates			Returns			Total
Ending balance at December 31, 2024	$	11,589		$	31,533		$	2,023		$	45,145
Provision related to sales in the current period		10,277			24,139			976			35,392
Adjustments related to prior period sales		439			(13	)		(382	)		44
Credits and payments made		(13,084	)		(28,467	)		(126	)		(41,677	)
Ending balance at March 31, 2025	$	9,221		$	27,192		$	2,491		$	38,904
Provision related to sales in the current period		12,138			30,823			1,083			44,044
Adjustments related to prior period sales		(66	)		185			852			971
Credits and payments made		(10,833	)		(27,623	)		(941	)		(39,397	)
Ending balance at June 30, 2025	$	10,460		$	30,577		$	3,485		$	44,522
Provision related to sales in the current period		12,695			38,426			1,152			52,273
Adjustments related to prior period sales		366			(12	)		(211	)		143
Credits and payments made		(12,436	)		(34,730	)		(2,324	)		(49,490	)
Ending balance at September 30, 2025	$	11,085		$	34,261		$	2,102		$	47,448

The following table summarizes activity in each of the product revenue allowance and reserve categories for the three and nine months ended September 30, 2024 (in thousands):


	Fees and patient assistance			Government and other rebates			Returns			Total
Ending balance at December 31, 2023	$	5,674		$	8,898		$	2,053		$	16,625
Provision related to sales in the current period		9,575			13,125			1,355			24,055
Adjustments related to prior period sales		146			(19	)		(96	)		31
Credits and payments made		(9,724	)		(9,906	)		(1,859	)		(21,489	)
Ending balance at March 31, 2024	$	5,671		$	12,098		$	1,453		$	19,222
Provision related to sales in the current period		10,025			17,777			1,039			28,841
Adjustments related to prior period sales		(131	)		354			(983	)		(760	)
Credits and payments made		(9,635	)		(14,640	)		(326	)		(24,601	)
Ending balance at June 30, 2024	$	5,930		$	15,589		$	1,183		$	22,702
Provision related to sales in the current period		11,455			25,364			1,380			38,199
Adjustments related to prior period sales		2,332			420			—			2,752
Credits and payments made		(12,078	)		(17,695	)		(979	)		(30,752	)
Ending balance at September 30, 2024	$	7,639		$	23,678		$	1,584		$	32,901

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


	Percent of Total Gross Product Revenues
	Three Months Ended September 30,		Nine Months Ended September 30,
	2025	2024	2025	2024
Customer A	13%	12%	12%	13%
Customer C	21%	17%	19%	18%
Customer D	58%	61%	59%	59%


	Percent of Product Sales Receivable
	As of September 30,
	2025	2024
Customer A	4%	3%
Customer C	21%	24%
Customer D	67%	61%

Schedule of Factoring of Accounts Receivable and Associated Fees

Factoring of accounts receivable and associated fees for the three and nine months ended September 30, 2025 and 2024 were as follows (in thousands):


	Three Months Ended September 30,					Nine Months Ended September 30,
	2025		2024			2025			2024
Accounts receivable sold	$	—	$	56,590		$	199,448		$	56,590
Less: factoring fees		—		(672	)		(2,433	)		(672	)
Net cash proceeds	$	—	$	55,918		$	197,015		$	55,918

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

3 Months Ended

9 Months Ended

Sep. 30, 2025

Jun. 30, 2025

Mar. 31, 2025

Sep. 30, 2024

Jun. 30, 2024

Mar. 31, 2024

Sep. 30, 2025

Sep. 30, 2024

Less:

Interest income

$ (4,376)

$ (2,889)

$ (9,641)

$ (9,377)

Interest expense

11,279

12,532

33,480

28,857

Income tax expense

602

592

1,409

876

Net income/(loss)

215,715

$ (42,151)

$ (92,225)

(57,445)

$ (37,657)

$ (66,423)

81,339

(161,525)

Reported Segment [Member]

Segment Reporting Information [Line Items]

Revenue

458,578

196,830

803,869

568,839

Less:

Internal research and development costs

19,225

20,217

63,867

61,084

Internal selling, general and administrative costs

44,938

42,814

135,133

132,942

External commercial costs

59,690

55,392

176,764

173,271

External research and development costs

36,982

56,499

122,573

150,653

External general and administrative costs

21,842

8,154

43,689

25,022

Other segment items

^[1]

24,495

33,489

72,499

79,222

Share-based compensation expense

28,186

27,475

82,757

87,814

Interest income

(4,376)

(2,889)

(9,641)

(9,377)

Interest expense

11,279

12,532

33,480

28,857

Income tax expense

602

592

1,409

876

Net income/(loss)

$ 215,715

$ (57,445)

$ 81,339

$ (161,525)

[1]	Other segment items include cost of sales and other expenses.

Prepaid and Other Current Assets - Summary of Prepaid and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Prepaid Expense and Other Assets, Current [Abstract]
Down payments for inventory	$ 970	$ 1,080
Prepaid research and development	20,156	7,780
Other prepaid expenses	10,434	9,508
Total prepaid assets	31,560	18,368
Royalties receivable	6,534	4,525
Receivable from collaboration agreement	2,563	2,272
Deposits and other current assets	1,061	4,847
Total other current assets	$ 10,158	$ 11,644

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2023	$ 194,521	$ 12	$ 3,035,539	$ (3,542)	$ (2,837,488)
Beginning balance, Shares at Dec. 31, 2023		119,556
Proceeds from settlement of capped call	98,763		98,763
Issuance of common stock upon exercise of stock options	9,477		9,477
Issuance of common stock upon exercise of stock options, shares		714
Vesting of restricted stock units, net of shares withheld for taxes	(28)		(28)
Vesting of restricted stock units, net of shares withheld for taxes. shares		997
Share-based compensation expense	30,349		30,349
Net loss	(66,423)				(66,423)
Foreign currency translation	17			17
Ending balance at Mar. 31, 2024	266,676	$ 12	3,174,100	(3,525)	(2,903,911)
Ending balance, Shares at Mar. 31, 2024		121,267
Beginning balance at Dec. 31, 2023	194,521	$ 12	3,035,539	(3,542)	(2,837,488)
Beginning balance, Shares at Dec. 31, 2023		119,556
Proceeds from settlement of capped call	98,763
Net loss	(161,525)
Foreign currency translation	402
Ending balance at Sep. 30, 2024	237,121	$ 12	3,239,262	(3,140)	(2,999,013)
Ending balance, Shares at Sep. 30, 2024		122,069
Beginning balance at Mar. 31, 2024	266,676	$ 12	3,174,100	(3,525)	(2,903,911)
Beginning balance, Shares at Mar. 31, 2024		121,267
Issuance of common stock upon exercise of stock options	1,962		1,962
Issuance of common stock upon exercise of stock options, shares		233
Vesting of restricted stock units, net of shares withheld for taxes. shares		102
Share-based compensation expense	29,990		29,990
Issuance of common stock under employee stock purchase plan	3,193		3,193
Issuance of common stock under employee stock purchase plan, shares		85
Net loss	(37,657)				(37,657)
Foreign currency translation	163			163
Ending balance at Jun. 30, 2024	264,327	$ 12	3,209,245	(3,362)	(2,941,568)
Ending balance, Shares at Jun. 30, 2024		121,687
Issuance of common stock upon exercise of stock options	2,556		2,556
Issuance of common stock upon exercise of stock options, shares		112
Vesting of restricted stock units, net of shares withheld for taxes	(14)		(14)
Vesting of restricted stock units, net of shares withheld for taxes. shares		270
Share-based compensation expense	27,475		27,475
Net loss	(57,445)				(57,445)
Foreign currency translation	222			222
Ending balance at Sep. 30, 2024	237,121	$ 12	3,239,262	(3,140)	(2,999,013)
Ending balance, Shares at Sep. 30, 2024		122,069
Beginning balance at Dec. 31, 2024	228,539	$ 12	3,267,201	(3,308)	(3,035,366)
Beginning balance, Shares at Dec. 31, 2024		124,495
Issuance of common stock upon exercise of stock options	281		281
Issuance of common stock upon exercise of stock options, shares		15
Vesting of restricted stock units, net of shares withheld for taxes	(7)		(7)
Vesting of restricted stock units, net of shares withheld for taxes. shares		1,151
Share-based compensation expense	27,374		27,374
Net loss	(92,225)				(92,225)
Foreign currency translation	254			254
Ending balance at Mar. 31, 2025	164,216	$ 12	3,294,849	(3,054)	(3,127,591)
Ending balance, Shares at Mar. 31, 2025		125,661
Beginning balance at Dec. 31, 2024	228,539	$ 12	3,267,201	(3,308)	(3,035,366)
Beginning balance, Shares at Dec. 31, 2024		124,495
Unrealized gain on pension benefits	137
Net loss	81,339
Foreign currency translation	771
Ending balance at Sep. 30, 2025	401,168	$ 12	3,357,583	(2,400)	(2,954,027)
Ending balance, Shares at Sep. 30, 2025		126,500
Beginning balance at Mar. 31, 2025	164,216	$ 12	3,294,849	(3,054)	(3,127,591)
Beginning balance, Shares at Mar. 31, 2025		125,661
Issuance of common stock upon exercise of stock options	4,367		4,367
Issuance of common stock upon exercise of stock options, shares		310
Vesting of restricted stock units, net of shares withheld for taxes. shares		82
Share-based compensation expense	27,197		27,197
Issuance of common stock under employee stock purchase plan	2,191		2,191
Issuance of common stock under employee stock purchase plan, shares		134
Net loss	(42,151)				(42,151)
Foreign currency translation	485			485
Ending balance at Jun. 30, 2025	156,305	$ 12	3,328,604	(2,569)	(3,169,742)
Ending balance, Shares at Jun. 30, 2025		126,187
Issuance of common stock upon exercise of stock options	797		797
Issuance of common stock upon exercise of stock options, shares		103
Vesting of restricted stock units, net of shares withheld for taxes	(4)		(4)
Vesting of restricted stock units, net of shares withheld for taxes. shares		210
Share-based compensation expense	28,186		28,186
Unrealized gain on pension benefits	137			137
Net loss	215,715				215,715
Foreign currency translation	32			32
Ending balance at Sep. 30, 2025	$ 401,168	$ 12	$ 3,357,583	$ (2,400)	$ (2,954,027)
Ending balance, Shares at Sep. 30, 2025		126,500

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Accounts receivable	$ 345,538		$ 345,538		$ 264,926
Revenue	458,578	$ 196,830	803,869	$ 568,839
Outstanding amount of sold accounts receivable			0		86,100
Accrued Expenses [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Product sales reserves	47,400		47,400		$ 45,100
Product [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Revenue	$ 177,755	$ 176,571	$ 499,042	$ 518,782

- 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.

+ References

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+ Details

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Payables and Accruals [Abstract]
Accrued research and development	$ 17,525	$ 22,782
Accrued royalties	7,059	7,147
Accrued payroll liabilities	32,542	40,888
Accrued goods received not invoiced	3,498	638
Product revenue reserves	47,448	45,145
Commercial costs	27,588	20,610
Other	4,662	2,974
Total accrued expenses	$ 140,322	$ 140,184

Fair Value Measurements - Additional Information (Detail) - Level 1 [Member] - Convertible Senior Notes [Member] - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible notes	$ 94.0	$ 102.3
Convertible notes, interest rate	3.50%	3.50%

Insider Trading Arrangements

3 Months Ended

Sep. 30, 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

Cedric G Francois
President and Chief Executive
Officer

Termination
8/14/2025

 Rule 10b5-1 trading arrangement

Sale

(1

)

(1

)

       Caroline Baumal
Chief Medical Officer

       Adoption
8/19/2025

        Rule 10b5-1 trading arrangement

       Sale

       Until 2/27/2027, or such earlier date upon which all transactions are completed or expire without execution

       Up to 14,698 shares

       James Chopas
Vice President, Corporate Controller and
Chief Accounting Officer

       Adoption
9/15/2025

        Rule 10b5-1 trading arrangement

       Sale

       Until 1/29/2027, or such earlier date upon which all transactions are completed or expire without execution

       Up to 25,947 shares

(1) This trading plan related to 358,090 shares of our common stock and had a scheduled expiration date of 7/31/2025.

Cedric G Francois [Member]

Trading Arrangements, by Individual

Name

Cedric G Francois

Title

President and Chief ExecutiveOfficer

Rule 10b5-1 Arrangement Terminated

true

Termination Date

8/14/2025

Expiration Date

7/31/2025

Aggregate Available

358,090

Caroline Baumal [Member]

Trading Arrangements, by Individual

Name

Caroline Baumal

Title

Chief Medical Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

8/19/2025

Expiration Date

2/27/2027

Aggregate Available

14,698

James Chopas [Member]

Trading Arrangements, by Individual

Name

James Chopas

Title

Vice President, Corporate Controller andChief Accounting Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

9/15/2025

Expiration Date

1/29/2027

Aggregate Available

25,947

Segment Information - Additional Information (Detail)	9 Months Ended
Segment Information - Additional Information (Detail)	Sep. 30, 2025 Segment
Segment Reporting [Abstract]
Number of operating segment	1
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	srt:ChiefExecutiveOfficerMember
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 the chief operating decision maker ("CODM") to analyze financial performance, make decisions, and allocate resources. The CODM is the chief executive officer (“CEO”). The Company’s CODM reviews consolidated net income/(loss) for purposes of assessing performance, making operating decisions, allocating resources, and planning and forecasting for future periods.
Segment Reporting, Expense Information Used by CODM, Type [Extensible Enumeration]	Net Income (Loss)

License and Collaboration Agreements

9 Months Ended

Sep. 30, 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, 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 or have performed drug product manufacturing of Licensed Products for development and for commercialization outside the United States and to manufacture or have manufactured drug substance under certain circumstances. For the three and nine months ended September 30, 2025 the Company recognized revenues of $5.2 million and $17.2 million, respectively, for the supply of Licensed Products to Sobi, which is included in Licensing and other revenue on the condensed consolidated statements of operations and comprehensive income/(loss). For the three and nine months ended September 30, 2024 the Company recognized revenues of $15.3 million and $36.2 million, respectively, for the supply of Licensed Products to Sobi, which is included in Licensing and other revenue on the condensed 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, of which the Company received $65.0 million and waived 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 (collectively, the “Company”) 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 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 in the Sobi Territory 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 Revenue from Contracts with Customers, 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 condensed consolidated statement of operations and comprehensive income/(loss) for the three and nine months ended September 30, 2025. The royalty revenues from the sales of Aspaveli will continue to be recorded as licensing and other revenue on the condensed consolidated statement of operations and comprehensive income/(loss) as the sales are made by Sobi outside of the United States.

Under the Sobi collaboration agreement, for the three and nine months ended September 30, 2025, the Company recognized $0.6 million and $12.6 million, respectively, of royalty revenue from sales of Aspaveli, which was sold by Sobi outside of the United States. For the three and nine months ended September 30, 2024, the Company recognized $5.0 million and $13.9 million, respectively, of royalty revenue from sales of Aspaveli, which was sold by Sobi outside of the United States.

The Company did not recognize any contra-research and development expense for the three and nine months ended September 30, 2025 and 2024. The Company doesn't expect to recognize the additional contra-research and development expense under this agreement.

University of Pennsylvania License Agreements

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.

In January 2021, the Company paid $25.0 million for a sublicense fee owed to Penn related to the Sobi collaboration agreement and another licensing transaction. In August 2021, the Company paid $1.0 million to Penn upon the achievement of a development milestone, net of a credit for the annual license maintenance payment. In June 2022, the Company paid an additional $5.0 million to Penn for a sublicense fee related to the Sobi collaboration agreement. In January 2023, the Company paid $1.0 million to Penn upon the achievement of a sales milestone for EMPAVELI in 2022. In January 2024, the Company paid $0.5 million for a sublicense fee owed to Penn related to Sobi obtaining regulatory approval in Japan. Additionally, in January 2024, the Company paid $1.5 million as a result of the achievement of a sales milestone for EMPAVELI and Aspaveli.

For the three and nine months ended September 30, 2025, the Company incurred royalty expense of $2.0 million and $5.3 million,

respectively, on sales of EMPAVELI and Aspaveli which is included in cost of sales on the condensed consolidated statements of operations and comprehensive income/(loss).

For the three and nine months ended September 30, 2024, the Company incurred royalty expense of $1.8 million and $5.0 million, respectively, on sales of EMPAVELI and Aspaveli which is included in cost of sales on the condensed 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.

In April 2023, the Company paid $2.3 million for the achievement of a regulatory milestone as a result of the FDA approval of SYFOVRE in February 2023. In 2023, the Company incurred $5.0 million as a result of the achievement of sales milestones for SYFOVRE of which the Company paid $2.0 million in October 2023 and the remaining $3.0 million in January 2024.

For the three and nine months ended September 30, 2025, the Company incurred royalty expense of $4.9 million and $14.1 million, respectively, on sales of SYFOVRE, which is included in cost of sales on the condensed consolidated statements of operations and comprehensive income/(loss).

For the three and nine months ended September 30, 2024, the Company incurred royalty expense of $4.9 million and $14.4 million, respectively, on sales of SYFOVRE, which is included in cost of sales on the condensed 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 agreed to pay a $50.0 million up-front, non-refundable payment to Beam, which the Company paid in July 2021. The Company paid an additional $25.0 million on the first anniversary of the Beam collaboration agreement in June 2022. 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 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 in 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.

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenue:
Revenue	$ 458,578	$ 196,830	$ 803,869	$ 568,839
Operating expenses:
Cost of sales	24,531	33,557	72,517	76,867
Research and development	68,186	88,569	221,621	251,216
Selling, general and administrative	142,678	121,984	403,162	379,571
Total operating expenses:	235,395	244,110	697,300	707,654
Net operating loss	223,183	(47,280)	106,569	(138,815)
Loss on extinguishment of development liability				(1,949)
Interest income	4,376	2,889	9,641	9,377
Interest expense	(11,279)	(12,532)	(33,480)	(28,857)
Other income/(expense), net	37	70	18	(405)
Net loss before taxes	216,317	(56,853)	82,748	(160,649)
Income tax expense	602	592	1,409	876
Net income/(loss)	215,715	(57,445)	81,339	(161,525)
Other comprehensive income/(loss):
Unrealized gain on pension benefits	137		137
Foreign currency translation	32	222	771	402
Total other comprehensive income	169	222	908	402
Comprehensive loss, net of tax	$ 215,884	$ (57,223)	$ 82,247	$ (161,123)
Net loss per common share, basic	$ 1.71	$ (0.46)	$ 0.65	$ (1.31)
Net loss per common share, diluted	$ 1.67	$ (0.46)	$ 0.65	$ (1.31)
Weighted-average number of common shares used in net loss per common share, basic	126,424	124,234	125,971	123,698
Weighted-average number of common shares used in net loss per common share, diluted	130,067	124,234	129,653	123,698
Product revenue, net [Member]
Revenue:
Revenue	$ 177,755	$ 176,571	$ 499,042	$ 518,782
Licensing and other revenue [Member]
Revenue:
Revenue	$ 280,823	$ 20,259	$ 304,827	$ 50,057

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]	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Gross Product Revenues [Member] \| Customer A [Member]
Revenue, Major Customer [Line Items]
Concentration risk	13.00%	12.00%	12.00%	13.00%
Gross Product Revenues [Member] \| Customer C [Member]
Revenue, Major Customer [Line Items]
Concentration risk	21.00%	17.00%	19.00%	18.00%
Gross Product Revenues [Member] \| Customer D [Member]
Revenue, Major Customer [Line Items]
Concentration risk	58.00%	61.00%	59.00%	59.00%
Product Sales Receivable [Member] \| Customer A [Member]
Revenue, Major Customer [Line Items]
Concentration risk			4.00%	3.00%
Product Sales Receivable [Member] \| Customer C [Member]
Revenue, Major Customer [Line Items]
Concentration risk			21.00%	24.00%
Product Sales Receivable [Member] \| Customer D [Member]
Revenue, Major Customer [Line Items]
Concentration risk			67.00%	61.00%

- 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

Accrued Expenses

9 Months Ended

Sep. 30, 2025

Payables and Accruals [Abstract]

Accrued Expenses

6. Accrued Expenses

Accrued expenses consisted of the following as of September 30, 2025 and December 31, 2024 (in thousands):


	September 30,		December 31,
	2025		2024
Accrued research and development	$	17,525	$	22,782
Accrued royalties		7,059		7,147
Accrued payroll liabilities		32,542		40,888
Accrued goods received not invoiced		3,498		638
Product revenue reserves		47,448		45,145
Commercial costs		27,588		20,610
Other		4,662		2,974
Total accrued expenses	$	140,322	$	140,184

Income Taxes

9 Months Ended

Sep. 30, 2025

Income Tax Disclosure [Abstract]

Income Taxes

9. Income Taxes

The income tax provision during interim periods is computed by applying an estimated annual effective tax rate to year-to-date pre-tax income, plus adjustments for significant unusual or infrequently occurring items, in accordance with FASB ASC Topic 740-270, Income Taxes – Interim Reporting. The income tax provision differs from the U.S. federal statutory rate of 21% primarily due to the effect of valuation allowance against the Company’s net deferred tax assets, which reduces the Company’s net tax benefit.

Deferred tax assets and deferred tax liabilities are determined based on temporary differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Company has recorded a full valuation allowance against its net deferred tax assets as of September 30, 2025 and December 31, 2024.

The Company does not recognize a tax benefit for uncertain tax positions unless it is more likely than not that the position will be sustained upon examination by tax authorities, including resolution of any related appeals or litigation processes, based on the technical merits of the position. The tax benefit that is recorded for these positions is measured at the largest amount of cumulative benefit that has greater than a 50 percent likelihood of being realized upon ultimate settlement. Deferred tax assets that do not meet these recognition criteria are not recorded and the Company recognizes a liability for uncertain tax positions that may result in tax payments. The Company has not recorded any amounts for unrecognized tax positions for the period ended September 30, 2025. The Company's policy is to review and update unrecognized tax positions as facts and circumstances change.

On July 4, 2025, The One Big Beautiful Bill Act (“OBBBA”) was enacted in the U.S. The OBBBA includes 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 new legislation did not have a material impact on the Company's tax provision during the quarter.

The Company recorded $0.6 million and $1.4 million of income tax expense for the three and nine months ended September 30, 2025, respectively, and $0.6 million and $0.9 million of income tax expense for the three and nine months ended September 30, 2024, respectively. The provision for income taxes consists of current tax expense, which relates primarily to the Company’s state and foreign tax jurisdictions where net operating loss carryforwards were either limited or not available.

- 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
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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
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-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
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-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
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-Paragraph 12C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12C

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
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-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)
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-URI https://asc.fasb.org/1943274/2147479360/740-10-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/740/tableOfContent

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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-Paragraph 2
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482603/740-30-50-2

+ Details

Segment Information (Tables)

9 Months Ended

Sep. 30, 2025

Segment Reporting [Abstract]

Schedule of segment financial information

The following table presents information about reported segment revenue, segment income/(loss), and significant segment expenses as provided to the CODM with respect to the Company’s single operating segment for the three and nine months ended September 30, 2025 and 2024:


	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2025			2024			2025			2024
Revenue	$	458,578		$	196,830		$	803,869		$	568,839
Less:
Internal research and development costs		19,225			20,217			63,867			61,084
Internal selling, general and administrative costs		44,938			42,814			135,133			132,942
External commercial costs		59,690			55,392			176,764			173,271
External research and development costs		36,982			56,499			122,573			150,653
External general and administrative costs		21,842			8,154			43,689			25,022
Other segment items (1)		24,495			33,489			72,499			79,222
Share-based compensation expense		28,186			27,475			82,757			87,814
Interest income		(4,376	)		(2,889	)		(9,641	)		(9,377	)
Interest expense		11,279			12,532			33,480			28,857
Income tax expense		602			592			1,409			876
Net income/(loss)	$	215,715		$	(57,445	)	$	81,339		$	(161,525	)

(1) Other segment items include cost of sales and other expenses.

Prepaid and Other Current Assets (Tables)

9 Months Ended

Sep. 30, 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 September 30, 2025 and December 31, 2024 (in thousands):


	September 30,		December 31,
	2025		2024
Down payments for inventory	$	970	$	1,080
Prepaid research and development		20,156		7,780
Other prepaid expenses		10,434		9,508
Total prepaid assets	$	31,560	$	18,368


	September 30,		December 31,
	2025		2024
Royalties receivable	$	6,534	$	4,525
Receivable from collaboration agreement		2,563		2,272
Deposits and other current assets		1,061		4,847
Total other current assets	$	10,158	$	11,644

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	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Numerator:
Net Income (Loss)	$ 215,715	$ (42,151)	$ (92,225)	$ (57,445)	$ (37,657)	$ (66,423)	$ 81,339	$ (161,525)
Adjustment - Interest expense on Convertible Notes	903			0			2,704	0
Adjusted Net income/(loss)	$ 216,618			$ (57,445)			$ 84,043	$ (161,525)
Denominator:
Weighted-average number of common shares used in net Income/(loss) per common share - basic	126,424			124,234			125,971	123,698
Weighted-average number of common shares used in net income/(loss) per common share - diluted	130,067			124,234			129,653	123,698
Net income/(loss) per common share - basic	$ 1.71			$ (0.46)			$ 0.65	$ (1.31)
Net income/(loss) per common share - diluted	$ 1.67			$ (0.46)			$ 0.65	$ (1.31)
Convertible notes
Denominator:
Incremental common shares attributable to conversion of debt	2,379			0			2,379	0
Employee Stock Option
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements	899			0			994	0
Unvested restricted stock units
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements	350			0			287	0
Shares expected to be purchased under employee stock purchase plan
Denominator:
Incremental common shares attributable to dilutive effect of share-based payment arrangements	15			0			22	0

Long-term Debt - Schedule of Interest Expense Recognized Related to Convertible Notes (Detail) - Convertible Senior Notes Due 2026 [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 81	$ 78	$ 239	$ 230
Contractual interest expense	822	822	2,465	2,465
Total interest expense	$ 903	$ 900	$ 2,704	$ 2,695

- 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

Inventory - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Inventory Disclosure [Abstract]
Raw materials	$ 52,183	$ 54,385
Semi-finished goods	107,463	92,872
Finished goods	4,082	9,860
Total inventory	$ 163,728	$ 157,117

Commitments and Contingencies - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Commitments And Contingencies [Line Items]
Accrued expenses	$ 140,322,000	$ 140,184,000
Other liabilities	3,257,000	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	$ 94,700,000
Non-cancellable purchase commitment period	2 years
Accrued expenses	$ 6,400,000
Other liabilities		$ 6,400,000
Other non-cancellable purchase commitments	$ 11,500,000
Vehicles [Member]
Commitments And Contingencies [Line Items]
Operating lease, term of contract	36 months

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2025

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following as of September 30, 2025 and December 31, 2024 (in thousands):


	September 30,		December 31,
	2025		2024
Accrued research and development	$	17,525	$	22,782
Accrued royalties		7,059		7,147
Accrued payroll liabilities		32,542		40,888
Accrued goods received not invoiced		3,498		638
Product revenue reserves		47,448		45,145
Commercial costs		27,588		20,610
Other		4,662		2,974
Total accrued expenses	$	140,322	$	140,184

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Income Tax Disclosure [Abstract]
U.S. federal statutory rate			21.00%
Minimum percentage of tax position likelihood of being realized upon examination by taxing authorities			50.00%
Unrecognized tax benefits	$ 0		$ 0
Income tax expense	$ 602,000	$ 592,000	$ 1,409,000	$ 876,000

- 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
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476153/220-40-55-4

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-Topic 220
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-URI https://asc.fasb.org/1943274/2147476153/220-40-55-21

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 220
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147476153/220-40-55-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section S50
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-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482964/270-10-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 32
-Subparagraph (ee)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-9

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Subparagraph (h)
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-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
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-Publisher FASB
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-SubTopic 10
-Topic 235
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

+ Details

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

9 Months Ended

Sep. 30, 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):


	Three Months Ended September 30,					Nine Months Ended September 30,
	2025		2024			2025		2024
Basic net income/(loss) per share
Numerator:
Net income/(loss)	$	215,715	$	(57,445	)	$	81,339	$	(161,525	)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic		126,424		124,234			125,971		123,698
Net income/(loss) per common share - basic	$	1.71	$	(0.46	)	$	0.65	$	(1.31	)

Diluted net income/(loss) per share
Numerator:
Net income/(loss)	$	215,715	$	(57,445	)	$	81,339	$	(161,525	)
Adjustment - Interest expense on Convertible Notes		903		—			2,704		—
Adjusted net income/(loss)	$	216,618	$	(57,445	)	$	84,043	$	(161,525	)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic		126,424		124,234			125,971		123,698
Convertible notes		2,379		—			2,379		—
Stock options to purchase common stock		899		—			994		—
Unvested restricted stock units		350		—			287		—
Shares expected to be purchased under employee stock purchase plan		15		—			22		—
Weighted-average number of common shares used in net income/(loss) per common share - diluted		130,067		124,234			129,653		123,698
Net income/(loss) per common share - diluted	$	1.67	$	(0.46	)	$	0.65	$	(1.31	)

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

The following table presents securities excluded from the calculation of diluted net income/(loss) per share due to their anti-dilutive effect (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Convertible notes		—		2,379		—		2,379
Stock options to purchase common stock		7,230		8,063		6,284		8,063
Unvested restricted stock units		3,942		4,017		4,328		4,017
Total		11,172		14,459		10,612		14,459

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Disaggregation of Product Revenue by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	$ 458,578	$ 196,830	$ 803,869	$ 568,839
EMPAVELI [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	26,827	24,611	67,315	74,733
SYFOVRE [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	150,928	151,960	431,727	444,049
Product revenue, net [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	$ 177,755	$ 176,571	$ 499,042	$ 518,782

- Definition

+ References

+ Details

Long-term Debt (Tables)

9 Months Ended

Sep. 30, 2025

Debt Disclosure [Abstract]

Schedule of Outstanding Balance of Convertible Notes

The outstanding balance of the Convertible Notes as of September 30, 2025 and December 31, 2024 consisted of the following (in thousands):


	September 30,			December 31,
	2025			2024
Principal	$	93,897		$	93,897
Less: debt discount and issuance costs, net		(316	)		(556	)
Net carrying amount	$	93,581		$	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 three and nine months ended September 30, 2025 and 2024 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Amortization of debt issuance costs	$	81	$	78	$	239	$	230
Contractual interest expense		822		822		2,465		2,465
Total interest expense	$	903	$	900	$	2,704	$	2,695

Summary of Credit Facility

The outstanding balance of the Credit Facility as of September 30, 2025 and December 31, 2024 consisted of the following (in thousands):


	September 30,			December 31,
	2025			2024
Principal	$	375,000		$	375,000
Less: debt discount and issuance costs		(13,909	)		(15,511	)
Net carrying amount	$	361,091		$	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 during the three and nine months ended September 30, 2025 and 2024 (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Amortization of debt issuance costs	$	556	$	581	$	1,602	$	742
Contractual interest expense		9,627		10,854		28,602		16,160
Total interest expense	$	10,183	$	11,435	$	30,204	$	16,902

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2025
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed 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 accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted and, accordingly, the condensed consolidated balance sheet as of December 31, 2024 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair presentation of the Company’s financial information. The results of operations for the three and nine months ended September 30, 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2025 or for any other interim period or for any other future year. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2024 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 28, 2025 (the “2024 Form 10-K”).
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 as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: accrued research and development expenses, reserves for variable consideration, share-based compensation expense and reserves for excess or obsolete inventories.
Recently Issued Accounting Standards	Recent Accounting Pronouncements issued not yet adopted In September 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“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 condensed 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 condensed 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, and subsequent amendments with ASU 2025-01, 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 statement. 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. 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 requires entities to provide additional information in the rate reconciliation and additional disaggregated disclosures about income taxes paid. This guidance requires public entities to disclose in their rate reconciliation table additional categories of information about federal, state, and foreign income taxes and to provide more details about the reconciling items in some categories if the items meet a quantitative threshold. The guidance is effective for annual periods beginning after December 15, 2024. The Company is currently evaluating the impact the adoption of this guidance will have on its disclosures.

- Definition

Disclosure of accounting policy for the use of estimates in the preparation of financial statements in conformity with generally accepted accounting principles.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478671/942-235-S50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
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-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477314/942-235-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482861/275-10-50-12

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482861/275-10-50-6

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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147482861/275-10-50-4

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-URI https://asc.fasb.org/1943274/2147482861/275-10-50-1

+ Details

Inventory (Tables)

9 Months Ended

Sep. 30, 2025

Inventory Disclosure [Abstract]

Schedule of Inventory

The Company’s inventory consisted of the following as of September 30, 2025 and December 31, 2024 (in thousands):


	September 30,		December 31,
	2025		2024
Raw materials	$	52,183	$	54,385
Semi-finished goods		107,463		92,872
Finished goods		4,082		9,860
Total inventory	$	163,728	$	157,117

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Operating Activities
Net income/(loss)	$ 81,339	$ (161,525)
Adjustments to reconcile net income/(loss) to net cash used in operating activities:
Share-based compensation expense	82,757	87,814
Loss on extinguishment of development liability		1,949
Depreciation expense	1,231	1,350
Amortization of discounts for credit facility	1,602	742
Amortization of discounts for convertible notes	239	230
Accretion of discount to development liability		8,936
Changes in operating assets and liabilities:
Accounts receivable	(80,605)	(72,569)
Inventory	(6,609)	(20,776)
Prepaid assets	(13,157)	15,022
Other current assets	1,642	10,651
Other assets	(4,181)	(81)
Right-of-use assets and lease liabilities	109	(7)
Accounts payable	28	(399)
Accrued expenses	(198)	12,072
Other current liabilities	0	1,903
Other liabilities	(4,694)	7,462
Net cash provided by/(used in) operating activities	59,503	(107,226)
Investing Activities
Purchase of property and equipment	(205)	(383)
Net cash used in investing activities	(205)	(383)
Financing Activities
Proceeds from credit facility		365,454
Payment of issuance cost for credit facility		(1,589)
Repayment of development liability		(326,533)
Proceeds from settlement of capped call		98,763
Proceeds from exercise of stock options	5,445	13,995
Proceeds from issuance of common stock under employee stock purchase plan	2,191	3,193
Payments of employee tax withholding related to equity-based compensation	(11)	(42)
Net cash provided by financing activities	7,625	153,241
Effect of exchange rate changes on cash, cash equivalents and restricted cash	1,066	306
Net (decrease)/ increase in cash, cash equivalents and restricted cash	67,989	45,938
Cash, cash equivalents and restricted cash at beginning of period	412,612	352,299
Cash, cash equivalents and restricted cash at end of period	480,601	398,237
Reconciliation of cash, cash equivalents and restricted cash to the consolidated balance sheets:
Cash and cash equivalents	479,171	396,864
Restricted cash	1,430	1,373
Total cash, cash equivalents, and restricted cash	480,601	398,237
Supplemental Disclosure of Financing Activities
Cash paid for interest	31,888	19,446
Issuance costs for credit facility incurred but not yet paid		5,625
Lease assets obtained in exchange for operating lease liabilities	6,457
Cash paid for income taxes	$ 847	$ 600

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 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	126,500,000	124,495,000
Common stock, outstanding	126,500,000	124,495,000

Commitments and Contingencies

9 Months Ended

Sep. 30, 2025

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

11. 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. In September 2024, the Company terminated the minimum purchase

obligation with NOF for 2025. Under these agreements, as of September 30, 2025, the Company is obligated to pay up to $94.7 million to these vendors over the next two years. As a result of the termination of the minimum purchase obligation with NOF, the Company incurred an expense of $6.4 million, which was included in cost of sales on the consolidated statements of operations and comprehensive loss for the year ended December 31, 2024. As this amount is due in January 2026, it is included in accounts payable on the condensed consolidated balance sheet as of September 30, 2025 and included in other liabilities on the condensed consolidated balance sheet as December 31, 2024.

In addition, the Company has other non-cancelable purchase agreements as of September 30, 2025, under which it is obligated to pay up to $11.5 million to vendors over the next five 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, where the case currently awaits further decision.

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.

Long-term Debt

9 Months Ended

Sep. 30, 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 semiannually 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 delivers 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.

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 increased in certain circumstances. The Company has not called for redemption or redeemed any of the Convertible Notes as of September 30, 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.

In January 2021, July 2021 and July 2022, the Company entered into separate, privately negotiated exchange agreements to modify the conversion terms with certain holders of its 2019 Convertible Notes and 2020 Convertible Notes. Under the terms of these exchange agreements, in January 2021, July 2021 and July 2022, the holders exchanged approximately $126.1 million of 2019 Convertible Notes, $201.1 million of 2019 Convertible Notes and 2020 Convertible Notes, and $98.1 million of 2020 Convertible Notes, respectively, in aggregate principal amount held by them for an aggregate of 3,906,869 shares, 5,992,217 shares and 3,027,018 shares, respectively, of common stock issued by the Company. The Company accounted for the conversion of the debt as an inducement by expensing the fair value of the shares that were issued in excess of the original terms of the Convertible Notes.

The conditional conversion feature of the Convertible Notes was not triggered as of September 30, 2025 and as of December 31, 2024.

As of September 30, 2025, 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 these as current as of September 30, 2025 and non-current as of December 31, 2024 on the Company’s unaudited condensed consolidated balance sheets.

The outstanding balance of the Convertible Notes as of September 30, 2025 and December 31, 2024 consisted of the following (in thousands):


	September 30,			December 31,
	2025			2024
Principal	$	93,897		$	93,897
Less: debt discount and issuance costs, net		(316	)		(556	)
Net carrying amount	$	93,581		$	93,341

The following table sets forth total interest expense recognized related to the Convertible Notes during the three and nine months ended September 30, 2025 and 2024 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Amortization of debt issuance costs	$	81	$	78	$	239	$	230
Contractual interest expense		822		822		2,465		2,465
Total interest expense	$	903	$	900	$	2,704	$	2,695

Capped Call Transactions

On September 11, 2019 and May 6, 2020, concurrently with the pricing of the 2019 Convertible Notes and the 2020 Convertible Notes, respectively, 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 September 30, 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 an annual rate equal to 3-month Secured Overnight Financing Rate ("SOFR") (subject to 1.00% floor), plus 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 ("SFJ").

The Credit Facility does not provide for scheduled amortization payments during the term. All principal will be due on the Maturity Date. The Company has 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 (one year from May 13, 2024) 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 “Consent”). In connection with the 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 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 September 30, 2025 and December 31, 2024 consisted of the following (in thousands):


	September 30,			December 31,
	2025			2024
Principal	$	375,000		$	375,000
Less: debt discount and issuance costs		(13,909	)		(15,511	)
Net carrying amount	$	361,091		$	359,489

The following table sets forth total interest expense recognized related to the Credit Facility during the three and nine months ended September 30, 2025 and 2024 (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Amortization of debt issuance costs	$	556	$	581	$	1,602	$	742
Contractual interest expense		9,627		10,854		28,602		16,160
Total interest expense	$	10,183	$	11,435	$	30,204	$	16,902

- 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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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 6
-Subparagraph (b)
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-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

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-Paragraph 6
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-Publisher FASB
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-Topic 405
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+ Details

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Current assets:
Cash and cash equivalents	$ 479,171	$ 411,290
Accounts receivable, net	345,538	264,926
Inventory	122,819	81,404
Prepaid assets	31,560	18,368
Restricted cash	1,430	1,322
Other current assets	10,158	11,644
Total current assets	990,676	788,954
Non-current assets:
Right-of-use assets	19,720	16,083
Property and equipment, net	1,927	2,952
Long-term inventory	40,909	75,713
Other assets	5,491	1,349
Total assets	1,058,723	885,051
Current liabilities:
Accounts payable	38,602	38,572
Accrued expenses	140,322	140,184
Convertible senior notes	93,581	0
Current portion of lease liabilities	7,022	6,753
Total current liabilities	279,527	185,509
Long-term liabilities:
Long-term credit facility	361,091	359,489
Convertible senior notes	0	93,341
Lease liabilities	13,680	10,201
Other liabilities	3,257	7,972
Total liabilities	657,555	656,512
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000 shares authorized, and no shares issued and outstanding at September 30, 2025 and December 31, 2024	0	0
Common stock, $0.0001 par value; 200,000 shares authorized at September 30, 2025 and December 31, 2024; 126,500 shares issued and outstanding at September 30, 2025, and 124,495 shares issued and outstanding at December 31, 2024	12	12
Additional paid-in capital	3,357,583	3,267,201
Accumulated other comprehensive loss	(2,400)	(3,308)
Accumulated deficit	(2,954,027)	(3,035,366)
Total stockholders' equity	401,168	228,539
Total liabilities and stockholders' equity	$ 1,058,723	$ 885,051

License and Collaboration Agreements - Additional Information (Detail)		1 Months Ended										3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2020 USD ($)	Sep. 30, 2025 USD ($) License	Aug. 31, 2025 USD ($)	Jan. 31, 2024 USD ($)	Oct. 31, 2023 USD ($)	Apr. 30, 2023 USD ($)	Jan. 31, 2023 USD ($)	Jun. 30, 2022 USD ($)	Apr. 30, 2022 USD ($)	Aug. 31, 2021 USD ($)	Jun. 30, 2021 Program	Sep. 30, 2025 USD ($) License	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) License	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jul. 01, 2025 USD ($) Price	Jul. 31, 2021 USD ($)	Jan. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)
SYFOVRE [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Regulatory milestone payments				$ 3,000,000	$ 2,000,000	$ 2,300,000
Royalty expense												$ 4,900,000	$ 4,900,000	$ 14,100,000	$ 14,400,000
Regulatory milestone incurred																$ 5,000,000
EMPAVELI and Aspaveli [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments based on annual sales milestones				1,500,000
Royalty expense												2,000,000	1,800,000	5,300,000	5,000,000
Swedish Orphan Biovitrum AB (Publ) [Member] \| Aspaveli [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalty Revenue												600,000	5,000,000	12,600,000	13,900,000
Royalty Agreement [Member] \| Swedish Orphan Biovitrum AB (Publ) [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment to be received																	$ 275,000,000
Aggregate amount agreed to be received upon European Medicines Agency approval																	$ 25,000,000
Collaboration and License Agreement [Member] \| Swedish Orphan Biovitrum AB (Publ) [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment	$ 250,000,000
Milestone payment received for achievement of regulatory development milestone									$ 50,000,000
Development cost reimbursement received														65,000,000
Waived Payment														$ 15,000,000
Royalties entitled to receive after first commercial sale of applicable licensed product period														10 years
Caps intial purchase price \| Price																	1.45
Percentage of royalty payment obligation																	90.00%
Percentage of royalty payment obligation reverted																	100.00%
Contract research and development expense												0	0	$ 0	0
Revenue recognized												5,200,000	$ 15,300,000	17,200,000	$ 36,200,000
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																				$ 915,000,000
Development cost reimbursement														80,000,000
University of Pennsylvania [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development milestone achievement										$ 1,000,000
Additional payment upon for sublicense fee related to collaboration agreement								$ 5,000,000
University of Pennsylvania [Member] \| EMPAVELI and Aspaveli [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments based on annual sales milestones							$ 1,000,000
University of Pennsylvania [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate milestones payments		$ 3,200,000										$ 3,200,000		3,200,000
Milestone payments based on annual sales milestones														$ 5,000,000
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		$ 1,700,000										$ 1,700,000		$ 1,700,000
Milestone payments based on annual sales milestones														$ 2,500,000
Sobi Agreement and Another Licensing Transaction [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Sublicense fee owed				$ 500,000															$ 25,000,000
Research Collaboration Agreement [Member] \| Beam Therapeutics Incorporation [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																		$ 50,000,000
Up-front payment on first anniversary of agreement on June 30, 2022								$ 25,000,000
Collaboration agreement maximum extendable term								2 years
Neonatal Fc Receptor [Member[ \| Beam Therapeutics Incorporation [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment		$ 3,800,000
Neonatal Fc Receptor [Member[ \| Beam Therapeutics Incorporation [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment received for achievement of regulatory development milestone			$ 168,800,000
Milestone payments based on annual sales milestones			$ 215,000,000

Long Term Debt - Summary of Interest Expense Recognized Related to Credit Facility (Detail) - Credit Facility [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 556	$ 581	$ 1,602	$ 742
Contractual interest expense	9,627	10,854	28,602	16,160
Total interest expense	$ 10,183	$ 11,435	$ 30,204	$ 16,902

- 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

Inventory

9 Months Ended

Sep. 30, 2025

Inventory Disclosure [Abstract]

Inventory

4. Inventory

The Company’s inventory consisted of the following as of September 30, 2025 and December 31, 2024 (in thousands):


	September 30,		December 31,
	2025		2024
Raw materials	$	52,183	$	54,385
Semi-finished goods		107,463		92,872
Finished goods		4,082		9,860
Total inventory	$	163,728	$	157,117

The Company's long-term inventory balance consists of raw materials as of September 30, 2025, and raw materials and semi-finished goods as of December 31, 2024, 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. The Company's reserve for excess and obsolete inventory was $19.6 million and $19.0 million as of September 30, 2025 and December 31, 2024, respectively.

Nature of Organization and Operations

9 Months Ended

Sep. 30, 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 (“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”).

Liquidity and Going Concern

The accompanying unaudited condensed consolidated financial statements have been prepared on the basis of the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. From inception to September 30, 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 supporting those activities and expenses incurred in connection with product launches and commercialization costs.

As of October 30, 2025, the date of issuance of these unaudited condensed consolidated financial statements, the Company believes that its cash and cash equivalents of $479.2 million as of September 30, 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 condensed consolidated financial statements.

Segment Information

9 Months Ended

Sep. 30, 2025

Segment Reporting [Abstract]

Segment Information

13. Segment Information

The Company operates as a single operating segment, which is 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. The Company defines its segment on the basis in which internally reported financial information is regularly reviewed by the chief operating decision maker ("CODM") to analyze financial performance, make decisions, and allocate resources. The CODM is the chief executive officer (“CEO”). The Company’s CODM reviews consolidated net income/(loss) for purposes of assessing performance, making operating decisions, allocating resources, and planning and forecasting for future periods.


	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2025			2024			2025			2024
Revenue	$	458,578		$	196,830		$	803,869		$	568,839
Less:
Internal research and development costs		19,225			20,217			63,867			61,084
Internal selling, general and administrative costs		44,938			42,814			135,133			132,942
External commercial costs		59,690			55,392			176,764			173,271
External research and development costs		36,982			56,499			122,573			150,653
External general and administrative costs		21,842			8,154			43,689			25,022
Other segment items (1)		24,495			33,489			72,499			79,222
Share-based compensation expense		28,186			27,475			82,757			87,814
Interest income		(4,376	)		(2,889	)		(9,641	)		(9,377	)
Interest expense		11,279			12,532			33,480			28,857
Income tax expense		602			592			1,409			876
Net income/(loss)	$	215,715		$	(57,445	)	$	81,339		$	(161,525	)

(1) Other segment items include cost of sales 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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+ Details

Long-term Debt - Financing Agreement and Credit Facility - Additional Information (Details) - USD ($)		9 Months Ended
	May 13, 2024	Sep. 30, 2025	Sep. 30, 2024
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
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
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%
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
Senior Secured Credit Facility [Member] \| Sixth Street Financing Agreement [Member] \| SOFR [Member]
Debt Instrument [Line Items]
Variable interest rate percentage on base rate	1.00%
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 - Schedule of Financial Instruments and the Related Fair Value Hierarchy of the Valuation Techniques Utilized (Detail) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	$ 215,630	$ 276,868
Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	215,630	276,868
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	215,630	276,868
Level 1 [Member] \| Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	$ 215,630	$ 276,868

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Pay vs Performance Disclosure
Net Income (Loss)	$ 215,715	$ (42,151)	$ (92,225)	$ (57,445)	$ (37,657)	$ (66,423)	$ 81,339	$ (161,525)

- Definition

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

+ References

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+ Details

Nature of Organization and Operations - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Nature Of Organization And Operations [Line Items]
Cash and cash equivalents	$ 479,171	$ 411,290	$ 396,864
Accumulated deficit	$ (2,954,027)	$ (3,035,366)

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Net Income/(Loss) per Common Share

9 Months Ended

Sep. 30, 2025

Earnings Per Share [Abstract]

Net Income/(Loss) per Common Share

12. Net Income/(Loss) per Common 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.

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


	Three Months Ended September 30,					Nine Months Ended September 30,
	2025		2024			2025		2024
Basic net income/(loss) per share
Numerator:
Net income/(loss)	$	215,715	$	(57,445	)	$	81,339	$	(161,525	)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic		126,424		124,234			125,971		123,698
Net income/(loss) per common share - basic	$	1.71	$	(0.46	)	$	0.65	$	(1.31	)

Diluted net income/(loss) per share
Numerator:
Net income/(loss)	$	215,715	$	(57,445	)	$	81,339	$	(161,525	)
Adjustment - Interest expense on Convertible Notes		903		—			2,704		—
Adjusted net income/(loss)	$	216,618	$	(57,445	)	$	84,043	$	(161,525	)
Denominator:
Weighted-average number of common shares used in net income/(loss) per common share - basic		126,424		124,234			125,971		123,698
Convertible notes		2,379		—			2,379		—
Stock options to purchase common stock		899		—			994		—
Unvested restricted stock units		350		—			287		—
Shares expected to be purchased under employee stock purchase plan		15		—			22		—
Weighted-average number of common shares used in net income/(loss) per common share - diluted		130,067		124,234			129,653		123,698
Net income/(loss) per common share - diluted	$	1.67	$	(0.46	)	$	0.65	$	(1.31	)

The following table presents securities excluded from the calculation of diluted net income/(loss) per share due to their anti-dilutive effect (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Convertible notes		—		2,379		—		2,379
Stock options to purchase common stock		7,230		8,063		6,284		8,063
Unvested restricted stock units		3,942		4,017		4,328		4,017
Total		11,172		14,459		10,612		14,459

Inventory - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Inventory Disclosure [Abstract]
Reserve for excess and obsolete inventory	$ 19.6	$ 19.0

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Factoring of Accounts Receivable and Associated Fees (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenue, Major Customer [Line Items]
Accounts receivable sold	$ 0	$ 56,590	$ 199,448	$ 56,590
Less: factoring fees	0	(672)	(2,433)	(672)
Net cash proceeds	$ 0	$ 55,918	$ 197,015	$ 55,918

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	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	11,172	14,459	10,612	14,459
Convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount		2,379		2,379
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	7,230	8,063	6,284	8,063
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	3,942	4,017	4,328	4,017

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Summary of Product Revenue Allowance and Reserve Categories (Detail) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024
Fees And Patient Assistance [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 10,460	$ 9,221	$ 11,589	$ 5,930	$ 5,671	$ 5,674
Provision related to sales in the current period	12,695	12,138	10,277	11,455	10,025	9,575
Adjustments related to prior period sales	366	(66)	439	2,332	(131)	146
Credits and payments made	(12,436)	(10,833)	(13,084)	(12,078)	(9,635)	(9,724)
Ending balance	11,085	10,460	9,221	7,639	5,930	5,671
Government and Other Rebates [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	30,577	27,192	31,533	15,589	12,098	8,898
Provision related to sales in the current period	38,426	30,823	24,139	25,364	17,777	13,125
Adjustments related to prior period sales	(12)	185	(13)	420	354	(19)
Credits and payments made	(34,730)	(27,623)	(28,467)	(17,695)	(14,640)	(9,906)
Ending balance	34,261	30,577	27,192	23,678	15,589	12,098
Returns [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	3,485	2,491	2,023	1,183	1,453	2,053
Provision related to sales in the current period	1,152	1,083	976	1,380	1,039	1,355
Adjustments related to prior period sales	(211)	852	(382)	0	(983)	(96)
Credits and payments made	(2,324)	(941)	(126)	(979)	(326)	(1,859)
Ending balance	2,102	3,485	2,491	1,584	1,183	1,453
Product Revenue Allowance and Reserves [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	44,522	38,904	45,145	22,702	19,222	16,625
Provision related to sales in the current period	52,273	44,044	35,392	38,199	28,841	24,055
Adjustments related to prior period sales	143	971	44	2,752	(760)	31
Credits and payments made	(49,490)	(39,397)	(41,677)	(30,752)	(24,601)	(21,489)
Ending balance	$ 47,448	$ 44,522	$ 38,904	$ 32,901	$ 22,702	$ 19,222

Long-term Debt - Summary of Credit Facility (Detail) - Credit Facility [Member] - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Principal	$ 375,000	$ 375,000
Less: debt discount and issuance costs	(13,909)	(15,511)
Net carrying amount	$ 361,091	$ 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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+ 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