0001847367-26-000010 | 10-Q | XBRL Viewer

Three Months Ended March 31,

Cash payments included in the measurement of operating lease liabilities

Print Document

Revenue (Details) $ in Thousands, ¥ in Billions	1 Months Ended		3 Months Ended
Revenue (Details) $ in Thousands, ¥ in Billions	Jan. 31, 2026 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2026 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($)	Mar. 31, 2025 JPY (¥)	Jan. 31, 2024 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized			$ 1,741	$ 17,389
Deferred revenue, current			6,328		$ 1,458
Deferred revenue, non-current					2,611
ACELYRIN
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Development, regulatory and commercial milestone payments							$ 157,500
Kaken \| Collaborative Arrangement for Product envu, formerly known as ESK-001
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Upfront, non-refundable payment		$ 20,000
Global development cost reimbursement		20,000		20,000
Maximum achievement of regulatory milestones		36,000		36,000
Maximum achievement of commercial milestones \| ¥						¥ 15.5
Amount allocated to license obligation		17,400		17,400
Amount allocated to Development Services Obligation		20,800		20,800
Amount allocated to Material Right Obligation		3,300		3,300
Revenue recognized			1,500	0
Deferred revenue, current			6,300		1,500
Deferred revenue, non-current			0		2,600
Estimated amount of transaction price unsatisfied			15,800
Kaken \| Collaborative Arrangement for Product envu, formerly known as ESK-001 \| Less than
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Collaboration revenue receivable			1		$ 100
Kaken \| Collaborative Arrangement for Product envu, formerly known as ESK-001 \| License obligation
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized			0	17,400
Kaken \| Collaborative Arrangement for Product envu, formerly known as ESK-001 \| Development services obligation
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized			1,700	0
Estimated amount of transaction price unsatisfied			12,500
Kaken \| Collaborative Arrangement for Product envu, formerly known as ESK-001 \| Material right obligation
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated amount of transaction price unsatisfied			$ 3,300
Kaken \| Collaborative Arrangement for Product envu, formerly known as ESK-001 \| Global development cost reimbursement in the dermatology field through the end of 2026
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Global development cost reimbursement		20,000		20,000
Kaken \| Collaborative Arrangement for Product envu, formerly known as ESK-001 \| Estimated global development cost reimbursement in the dermatology field after 2026
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Global development cost reimbursement		$ 1,500		$ 1,500
Climb Bio
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Development milestone payment in dispute	$ 3,000
Development milestone payment to seek	$ 3,000

Organization and Nature of the Business

3 Months Ended

Mar. 31, 2026

Organization and Nature of the Business

Organization and Nature of the Business

1.	Organization and Nature of the Business

Organization and Business

Alumis Inc. (the “Company”) is a clinical stage biopharmaceutical company focused on identifying, acquiring, and accelerating the development and commercialization of transformative medicines for autoimmune disorders. The Company leverages its proprietary precision data analytics platform, biological insights, and a team of experts with deep experience in precision medicine drug discovery, development, and immunology, in its mission to create medicines that significantly improve the lives of patients by replacing broad immunosuppression with targeted therapies.

The Company was founded on January 29, 2021, as a Delaware corporation under the name FL2021-001, Inc. FL2021-001, Inc.’s name was changed to Esker Therapeutics, Inc. on March 8, 2021, and to Alumis Inc. on January 6, 2022. The Company is headquartered in South San Francisco, California.

As of March 31, 2026, the Company had two wholly owned subsidiaries, ACELYRIN, Inc. (“ACELYRIN”), a Delaware corporation incorporated on July 27, 2020 and its wholly owned subsidiary, WH2, LLC. Arrow Merger Sub, Inc. (“Merger Sub”), the Company’s wholly owned subsidiary incorporated in January 2025, was merged with and into ACELYRIN in May 2025.

ACELYRIN Merger

On February 6, 2025, the Company entered into an Agreement and Plan of Merger, and, on April 20, 2025, the Company entered into an Amendment to Agreement and Plan of Merger (collectively the “Merger Agreement”) with ACELYRIN and Merger Sub, a Delaware corporation and a direct wholly owned subsidiary of the Company. Under the terms of the Merger Agreement, Merger Sub merged with and into ACELYRIN, with ACELYRIN continuing as a direct wholly owned subsidiary of the Company (the “ACELYRIN Merger”). The Merger Agreement was approved by the disinterested directors on the Company’s board of directors and the board of directors of ACELYRIN and was approved by the stockholders of each company on May 13, 2025. On May 21, 2025, the Company completed the ACELYRIN Merger with ACELYRIN for a purchase consideration of $238.1 million that included the issuance of 48,653,549 shares of the Company’s common stock and the fair value of replacement awards attributable to pre-combination services, to acquire net assets with a fair value of $426.0 million. See Note 3 for additional information.

Public Offering of Common Stock

On January 7, 2026, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Morgan Stanley & Co. LLC, Leerink Partners LLC and Cantor Fitzgerald & Co. (“Cantor”) (collectively the “Underwriters”), relating to the issuance and sale in a public offering of 17,650,000 shares of the Company’s common stock at a price of $17.00 per share. In addition, the Company granted the Underwriters an option, exercisable for 30 days, to purchase up to 2,647,500 additional shares of common stock at the public offering price, less the underwriting discounts and commissions, which was exercised in full on January 8, 2026. On January 9, 2026, the offering closed and the Company received net proceeds of $324.4 million, after deducting underwriting discounts and commissions.

The offering was made pursuant to a shelf registration statement on Form S-3 (File No. 333-288510) that was filed with the SEC on July 3, 2025 and declared effective by the SEC on August 19, 2025, and related prospectus and prospectus supplement thereunder.

Controlled Equity Offering^SM

On March 18, 2026, the Company entered into a Controlled Equity Offering^SM Sales Agreement (the “Sales Agreement”) with Cantor as sales agent, pursuant to which the Company may offer and sell, from time to time through Cantor, at its option, shares of its common stock having an aggregate offering price of up to $300.0 million (the “ATM Shares”). The sales of the ATM Shares will be made by any method permitted that is deemed to be an “at-the-market” equity offering as defined in Rule 415(a)(4) promulgated under the Securities Act, including sales made directly on or through the Nasdaq Global Select Market. The Company agreed to pay Cantor a commission of up to 3.0% of the aggregate gross proceeds from any ATM Shares sold by Cantor. As of March 31, 2026, no ATM Shares were sold under the Sales Agreement.

Liquidity

The Company has incurred negative operating cash flows and significant losses from operations since its inception. For the three months ended March 31, 2026 and 2025, the Company incurred net losses of $93.1 million and $99.0 million, respectively. Cash used in operating activities was $87.1 million and $80.4 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, the Company had an accumulated deficit of $994.9 million.

The Company has historically funded its operations primarily through the issuance of common stock, including in connection with the ACELYRIN Merger and the Company’s initial public offering (“IPO”) and a concurrent private placement transaction, the issuance of redeemable convertible preferred stock and convertible promissory notes in private placements, and, most recently, the public offering of common stock which closed on January 9, 2026, as well as cash payments received under the collaboration and license agreement (the “Kaken Collaboration Agreement”) with Kaken Pharmaceutical Co., Ltd. (“Kaken”). The Company expects to continue to incur substantial losses for the foreseeable future, and its ability to achieve and sustain profitability will depend on the successful development, approval, and commercialization of any product candidates it may develop, and on the achievement of sufficient revenue to support its cost structure. The Company may never achieve profitability and, unless and until it does, it will need to continue to raise additional capital. The Company believes that, based on its current operating plan, its existing cash, cash equivalents and marketable securities of $569.5 million as of March 31, 2026, will be sufficient to meet its operating and capital requirements for at least 12 months from the date of issuance of these unaudited condensed consolidated financial statements.

The Company will need to raise significant additional capital to fund ongoing research and development activities and maintain future operations. The Company’s management continuously monitors and, where necessary, may reduce its operating expenses in response to its clinical development progress and its ability and need to raise additional capital through a combination of public and private equity, debt financings, strategic alliances and licensing arrangements. For example, should any of the Company’s ongoing trials not meet its clinical development objectives, the Company may scale back or discontinue related activities and reallocate its working capital to extend its ability to meet its operating and capital requirements. The Company’s ability to access capital when needed is not assured and, if capital is not available to the Company when, and in the amounts, needed, on the terms which are favorable, the Company could be required to delay, scale back, or abandon some or all of its planned development programs and other operations, which could materially harm the Company’s business, financial condition and results of operations.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Cash flows from operating activities
Net loss	$ (93,053)	$ (98,963)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	12,339	6,995
Net accretion of discounts on marketable securities	(1,961)	(983)
Depreciation and amortization	871	843
Non-cash lease expense	575	266
Impairment of long-lived assets	444
Changes in operating assets and liabilities:
Research and development prepaid expenses	(436)	561
Other prepaid expenses and other assets	780	583
Other assets, non-current	(545)	(38)
Accounts payable	1,432	(2,151)
Deferred revenue	2,259	2,611
Research and development accrued expenses	1,178	5,550
Other accrued expenses and current liabilities	(9,716)	4,988
Operating lease liabilities	(1,249)	(617)
Net cash used in operating activities	(87,082)	(80,355)
Cash flows from investing activities
Maturities of marketable securities	142,862	64,000
Purchases of marketable securities	(428,384)	(24,535)
Purchases of property and equipment	(164)	(37)
Net cash (used in) provided by investing activities	(285,686)	39,428
Cash flows from financing activities
Proceeds from public offering of common stock, net of underwriter discounts, commissions and offering costs	323,797
Proceeds from issuance of common stock upon exercise of stock options	23,191
Net cash provided by financing activities	346,988
Net decrease in cash, cash equivalents and restricted cash	(25,780)	(40,927)
Cash, cash equivalents and restricted cash at beginning of period	91,053	170,632
Cash, cash equivalents and restricted cash at end of period	65,273	129,705
Supplemental disclosures:
Receivable recorded for stock option exercises pending settlement	74
Purchases of property and equipment in accounts payable and other accrued expenses and current liabilities	50	165
Vesting of early exercised stock options and unvested restricted shares of common stock	29	226
Right-of-use assets obtained in exchange for operating lease liabilities		1,776
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	63,885	128,543
Restricted cash	86
Restricted cash, non-current	1,302	1,162
Total cash, cash equivalents and restricted cash	$ 65,273	$ 129,705

Stock-Based Compensation - Early Exercise of Employee Options (Details) - Early exercise employee option - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Early Exercisable Shares, Number of shares:
Unvested shares outstanding at beginning of the period (shares)	13,681
Vested (shares)	(3,201)
Unvested shares outstanding at end of the period (shares)	10,480
Early Exercisable Shares, Weighted-Average Exercise Price Per Share:
Exercise price at the beginning of the period ($ per share)	$ 9.01
Vested ($ per share)	9.13
Exercise price at the end of the period ($ per share)	$ 8.97
Share repurchase liability related to the unvested shares	$ 0.1	$ 0.1

Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended
Segment Reporting (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025
Revenue:
Total revenue	$ 1,741	$ 17,389
Internal costs
Total research and development expense	81,540	96,622
General and administrative expenses	18,610	22,295
Total operating expenses	100,150	118,917
Loss from operations	(98,409)	(101,528)
Total other income (expense), net	5,356	2,565
Net loss	(93,053)	(98,963)
License
Revenue:
Total revenue		17,389
Collaboration
Revenue:
Total revenue	1,741
Single reportable segment
Revenue:
Total revenue	1,741	17,389
External costs
CROs, CMOs and clinical trials	40,928	65,072
Professional consulting services	6,804	6,403
Other research and development costs	2,370	2,296
Internal costs
Personnel-related costs	26,065	17,659
Facilities and overhead costs	5,373	5,192
Total research and development expense	81,540	96,622
General and administrative expenses	18,610	22,295
Total operating expenses	100,150	118,917
Loss from operations	(98,409)	(101,528)
Total other income (expense), net	5,356	2,565
Net loss before income taxes	(93,053)	(98,963)
Net loss	(93,053)	(98,963)
Single reportable segment \| License
Revenue:
Total revenue		$ 17,389
Single reportable segment \| Collaboration
Revenue:
Total revenue	$ 1,741

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Related Party Transactions
Research and development expenses	$ 81,540	$ 96,622
Related party
Related Party Transactions
Research and development expenses	$ 66	262
Related party \| Foresite labs
Related Party Transactions
Automatic renewal term	1 year
Research and development expenses	$ 100	$ 300
Research and development accrued expenses	$ 0		$ 0

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-3

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

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-13

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

+ Details

Balance Sheet Components

3 Months Ended

Mar. 31, 2026

Balance Sheet Components

Balance Sheet Components

6.Balance Sheet Components

Restricted Cash

Restricted cash includes cash held at financial institutions that is pledged as collateral for stand-by letters of credit of $1.4

million and $1.3 million related to lease commitments as of March 31, 2026 and December 31, 2025, respectively. The cash will be restricted until the termination or modification of the related lease agreements. Restricted cash of $0.1 million was classified as restricted cash, current and $1.3 million was classified as restricted cash, non-current in the condensed consolidated balance sheet as of March 31, 2026. Restricted cash of $1.3 million was classified as restricted cash, non-current in the condensed consolidated balance sheet as of December 31, 2025.

Other Prepaid Expenses and Current Assets

Other prepaid expenses and current assets consisted of the following as of March 31, 2026 and December 31, 2025 (in thousands):


		March 31,			December 31,
		2026			2025
Interest receivable		$	2,231		$	1,343
Prepaid subscriptions			1,963			2,088
Tax receivable			499			740
Prepaid insurance			413			744
Prepaid credit voucher for clinical manufacturing			268			683
Other			659			1,142
Total other prepaid expenses and current assets		$	6,033		$	6,740

The prepaid credit voucher for clinical manufacturing was received by ACELYRIN in the third quarter of 2024 as part of an agreement to cancel certain services with a vendor under a manufacturing agreement related to the suspension of development of certain ACELYRIN programs. The prepaid credit voucher for clinical manufacturing may be used to settle invoices for services and raw materials from this vendor related to the lonigutamab product candidate. As of March 31, 2026, the prepaid credit voucher for clinical manufacturing included $0.3 million classified in other prepaid expenses and current assets and $5.8 million included in other assets, non-current.

Property and Equipment, Net

Property and equipment, net consisted of the following as of March 31, 2026 and December 31, 2025 (in thousands):


		Estimated Useful Life		March 31,			December 31,
		(in years)		2026			2025
Leasehold improvements		Shorter of useful life or lease term		$	17,870		$	17,655
Laboratory equipment		5			5,843			5,843
Furniture and fixtures		5			1,709			1,709
Computer equipment		5			896			896
Capitalized software		3			75			75
Total property and equipment, gross					26,393			26,178
Less: Accumulated depreciation and amortization					(8,859)			(7,988)
Total property and equipment, net				$	17,534		$	18,190

Depreciation and amortization expense was $0.9 million and $0.8 million for the three months ended March 31, 2026 and 2025, respectively.

Other Accrued Expenses and Current Liabilities

Other accrued expenses and current liabilities consisted of the following as of March 31, 2026 and December 31, 2025 (in thousands):


		March 31,			December 31,
		2026			2025
Accrued professional services		$	6,699		$	4,397
Accrued personnel and related expenses			5,528			17,581
Severance liability			—			244
Other			361			81
Total other accrued expenses and current liabilities		$	12,588		$	22,303

Summary of Significant Accounting Policies and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2026
Summary of Significant Accounting Policies and Basis of Presentation
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements and accompanying notes are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the SEC regarding interim financial reporting and do not contain all information that is included in the annual financial statements and notes thereto of the Company. The Company’s unaudited condensed consolidated financial statements include the accounts of its subsidiaries, and all intercompany transactions were eliminated. The Company’s unaudited condensed consolidated financial statements include the accounts of its subsidiaries ACELYRIN and WH2, LLC after the closing of the ACELYRIN Merger, and the accounts of Merger Sub from its incorporation in January 2025 until the ACELYRIN Merger. WH2, LLC has not had any operations or any balances since the closing of the ACELYRIN Merger. The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position as of March 31, 2026 and its results of operations and its cash flows for the three months ended March 31, 2026 and 2025. The condensed balance sheet as of December 31, 2025, included in this filing, was derived from audited annual consolidated financial statements but does not include all disclosures required by U.S. GAAP. The results of operations for the three months ended March 31, 2026 and 2025 are not necessarily indicative of the results of operations to be expected for the full year or for any other subsequent interim period. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).
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, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates estimates and assumptions, including but not limited to those related to accrued research and development expenses, valuation of acquired in-process research and development (“IPR&D”) intangible assets, revenue recognition, and stock-based compensation expense. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates.
Segment and Geographical Information	Segment and Geographical Information The Company operates and manages its business as one reportable and operating segment, which is the business of researching and developing medicines for autoimmune disorders. The chief executive officer, who is the chief operating decision maker (“CODM”), reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. See Note 14 for additional information. All of the Company’s long-lived assets are located in the United States.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments which potentially subject the Company to concentration of credit risk consist primarily of cash and cash equivalents, investments in marketable securities, accounts receivable and restricted cash. The Company maintains bank deposits in federally insured financial institutions and certain of these deposits exceed federally insured limits. To date, the Company has not experienced any losses on its deposits of cash and periodically evaluates the creditworthiness of the financial institutions at which its bank deposits are maintained. The Company also invests in money market funds, U.S. Treasury obligations, commercial paper, corporate debt obligations, supranational debt obligations, and government development bank obligations, which can be subject to certain credit risks. The Company mitigates credit risk by limiting its exposure to any one issuer and monitoring the ongoing creditworthiness of the financial institutions at which investments are maintained and of the issuers of the marketable securities. To date, the Company has not experienced any loss of principal on its financial instruments. The Company considers a customer to be significant when revenues from that customer represent 10% or more of total revenues. All of the Company’s revenues are currently earned under its license and collaboration agreement with Kaken. As a result, the Company is subject to customer concentration risk. To date, the Company has not incurred any credit losses in connection with the Kaken Collaboration Agreement.
Risks and Uncertainties	Risks and Uncertainties The Company is subject to certain risks and uncertainties, including, but not limited to, changes in any of the following areas that the Company believes could have a material adverse effect on the future financial position or results of operations: the Company’s ability to advance the development of its proprietary precision data analytics platform, timing and ability to advance its product candidates through preclinical and clinical development; costs and timelines associated with the manufacturing of clinical supplies; regulatory approval, market acceptance of, and reimbursement for, any product candidates the Company may develop; performance of third-party vendors; competition from pharmaceutical or other biotechnology companies with greater financial resources or expertise; protection of intellectual property; litigation or claims against the Company based on intellectual property or other factors; and its ability to attract and retain employees necessary to support its growth. Further, the Company’s business and results of operations may be affected by worldwide economic conditions, which may continue to be impacted by global macroeconomic challenges and uncertainty in the markets, including international trade policies and tariffs, severely diminished liquidity and credit availability, rising inflation and monetary supply shifts, rising interest rates, labor shortages, declines in consumer confidence, declines in economic growth, increases in unemployment rates, recession risks and uncertainty about economic and geopolitical stability. The United States and other countries have imposed and may continue to impose new trade restrictions and export regulations, have levied tariffs and taxes on certain goods, including tariffs targeting pharmaceutical products and related inputs, and could continue to significantly increase tariffs on a broad array of goods. Similarly, the Company’s financial condition and results of operations may continue to be affected by global volatility and general market disruption resulting from geopolitical tensions, such as the ongoing Russia-Ukraine military conflict and the ongoing military conflict involving the U.S., Israel and Iran. In particular, the continued escalation of hostilities in the Middle East, including involving Iran, could further disrupt global energy markets, fuel prices, transportation networks, and supply chains, which may disrupt or otherwise negatively impact the Company’s supply chain and increase its costs. These worldwide economic conditions, global trade policies and geopolitical developments may negatively impact the Company’s business, financial position and results of operations.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the JOBS Act, and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and private companies, the Company will adopt the new or revised standard at the time private companies adopt the new or revised standard and will do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for private companies. Recently Adopted Accounting Pronouncements In July 2025, the FASB issued ASU 2025‑05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets (“ASU 2025-05”) which provides a practical expedient and accounting policy election related to estimating expected credit losses for certain receivables and contract assets. The Company adopted ASU 2025‑05 as of January 1, 2026. Adoption of this guidance did not have a material impact on the Company’s consolidated financial statements. Recently Issued and Not Yet Adopted Accounting Pronouncements In November 2024, the FASB issued ASU No. 2024-03, Disaggregation of Income Statement Expenses (Topic 220) (“ASU 2024-03”), requiring that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. The amendments of ASU 2024-03 are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The requirements of ASU 2024-03 may be applied either prospectively to financial statements issued for reporting periods after the effective date or retrospectively to any or all prior periods presented in the financial statements. The Company is currently evaluating the impact of adopting ASU 2024-03 on its consolidated financial statements and disclosures. In December 2025, the FASB issued ASU No. 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements (“ASU 2025-11”), which clarifies the form and content of interim financial statements, adds a comprehensive list of required interim disclosures, and provides a disclosure principle for condensed interim financial statements. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. Early adoption is permitted and, on adoption, can be applied either prospectively or retrospectively to any or all periods presented in the financial statements. The Company is currently evaluating the impact of the new standard on the Company's consolidated financial statements and related disclosures.

- Definition

Disclosure of accounting policy for segment reporting.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-41

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-29

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-29

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-29

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (bb)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-29

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 54
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-54

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 36
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-36

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-29

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-29

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-29

+ Details

- 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
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477314/942-235-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-12

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-9

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482836/275-10-55-6

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-4

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-SubTopic 10
-Topic 275
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-SubTopic 10
-Topic 275
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-1

+ Details

Commitments and Contingent Liabilities (Tables)

3 Months Ended

Mar. 31, 2026

Commitments and Contingent Liabilities

Summary of components of lease costs

The components of lease costs were as follows (in thousands):


		Three Months Ended March 31,
		2026			2025
Operating lease costs		$	1,299		$	1,115
Variable lease costs			279			351
Total lease costs		$	1,578		$	1,466

Schedule of supplemental cash flow information related to the operating leases

Supplemental cash flow information related to the operating leases was as follows (in thousands):

Schedule of weighted-average remaining lease term and incremental borrowing rate for the operating leases


		March 31,		December 31,
		2026		2025
Weighted-average remaining lease term (years)		6.6		6.8
Weighted-average incremental borrowing rate		11.6	%	11.6	%

Schedule of future minimum lease payments under non-cancelable leases

Future minimum lease payments under non-cancelable leases as of March 31, 2026, were as detailed below (in thousands):


2026 (remainder of the year)	$	6,250
2027		7,648
2028		7,765
2029		7,205
2030		5,848
Thereafter		16,009
Total undiscounted lease payments		50,725
Less: Imputed interest		(15,061)
Total operating lease liabilities	$	35,664

Balance Sheet Components - Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025
Balance Sheet Components
Restricted cash - current	$ 86	$ 82
Restricted cash - non-current	1,302	1,301	$ 1,162
Asset pledged as collateral for lease commitments
Balance Sheet Components
Restricted cash	1,400	1,300
Restricted cash - current	100
Restricted cash - non-current	$ 1,300	$ 1,300

Organization and Nature of the Business (Details) $ / shares in Units, $ in Thousands					3 Months Ended
	Mar. 18, 2026 USD ($)	Jan. 09, 2026 USD ($)	Jan. 07, 2026 $ / shares shares	May 21, 2025 USD ($) shares	Mar. 31, 2026 USD ($) subsidiary shares	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($)
Organization and Nature of the Business
Number of wholly owned subsidiaries \| subsidiary					2
Net proceeds					$ 323,797
Net loss					(93,053)	$ (98,963)
Cash used in operating activities					87,082	$ 80,355
Accumulated deficit					994,929		$ 901,876
Cash, cash equivalents and marketable securities					$ 569,500
ACELYRIN
Organization and Nature of the Business
Purchase consideration				$ 238,077
Issuance of common stock (in shares) \| shares				48,653,549
Fair value of net assets				$ 425,984
Public Offering
Organization and Nature of the Business
Number of shares issued and sold \| shares			17,650,000
Issue price per share \| $ / shares			$ 17
Underwriters option period			30 days
Maximum number of common stock for an option to purchase \| shares			2,647,500
Net proceeds		$ 324,400
ATM shares
Organization and Nature of the Business
Aggregate offering price	$ 300,000
Percentage of commission to be paid	3.00%
Number of shares issued and sold \| shares					0

Fair Value Measurements - Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Assets:
Marketable securities, current	$ 459,058	$ 218,831
Marketable securities, non-current	46,603
U.S. Treasury obligations
Assets:
Marketable securities, current	308,831	148,481
Marketable securities, non-current	30,093
Corporate debt obligations
Assets:
Marketable securities, current	85,849	30,744
Marketable securities, non-current	16,510
Commercial paper
Assets:
Marketable securities, current	52,402	27,672
Supranational debt obligations
Assets:
Marketable securities, current	7,971	7,922
Government development bank obligations
Assets:
Marketable securities, current	4,005	4,012
Recurring
Assets:
Total assets	564,397	304,531
Recurring \| Money market funds
Assets:
Cash equivalents	58,736	81,729
Recurring \| U.S. Treasury obligations
Assets:
Cash equivalents		3,971
Marketable securities, current	308,831	148,482
Marketable securities, non-current	30,093
Recurring \| Corporate debt obligations
Assets:
Marketable securities, current	85,849	30,743
Marketable securities, non-current	16,510
Recurring \| Commercial paper
Assets:
Marketable securities, current	52,402	27,672
Recurring \| Supranational debt obligations
Assets:
Marketable securities, current	7,971	7,922
Recurring \| Government development bank obligations
Assets:
Marketable securities, current	4,005	4,012
Level 1 \| Recurring
Assets:
Total assets	296,070	196,509
Level 1 \| Recurring \| Money market funds
Assets:
Cash equivalents	58,736	81,729
Level 1 \| Recurring \| U.S. Treasury obligations
Assets:
Cash equivalents		3,971
Marketable securities, current	207,241	110,809
Marketable securities, non-current	30,093
Level 2 \| Recurring
Assets:
Total assets	268,327	108,022
Level 2 \| Recurring \| U.S. Treasury obligations
Assets:
Marketable securities, current	101,590	37,673
Level 2 \| Recurring \| Corporate debt obligations
Assets:
Marketable securities, current	85,849	30,743
Marketable securities, non-current	16,510
Level 2 \| Recurring \| Commercial paper
Assets:
Marketable securities, current	52,402	27,672
Level 2 \| Recurring \| Supranational debt obligations
Assets:
Marketable securities, current	7,971	7,922
Level 2 \| Recurring \| Government development bank obligations
Assets:
Marketable securities, current	$ 4,005	$ 4,012

Acquisition (Details) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
Acquisition (Details) $ / shares in Units, $ in Thousands	May 21, 2025 USD ($) lease installment $ / shares shares	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($) shares	Mar. 31, 2026 shares
Acquisitions
Common stock reserved for future issuance \| shares			31,068,650	35,125,582
ACELYRIN
Acquisitions
Number of shares issued in exchange \| shares	48,653,549
Stock option, exercise price ($ per share) \| $ / shares	$ 18
Exchange ratio	0.4814
Fair value of IPR&D asset	$ 50,959
Discount rate	24.00%
Credit voucher acquired, balance	$ 11,400
Number of operating leases acquired \| lease	2
Lease liability fair value adjustment, short term portion	$ 200
Lease liability fair value adjustment, long term portion	500
Right of use asset fair value adjustment	100
Gain on bargain purchase	187,907
Deferred income tax liability	$ 10,701
ACELYRIN \| General and administrative expenses
Acquisitions
Merger transaction costs		$ 7,700
ACELYRIN \| Severance Plan
Acquisitions
Entitled period (in months)	12 months
Maximum options exercise periods extension period, post-termination (in months)	12 months
Severance cash obligations	$ 11,900
Severance cash obligations payment period (in months)	12 months
Additional stock-based compensation			$ 13,100
ACELYRIN \| Severance Plan \| General and administrative expenses
Acquisitions
Severance cost			6,500
ACELYRIN \| Severance Plan \| Research and development expenses
Acquisitions
Severance cost			$ 5,400
ACELYRIN \| RSUs
Acquisitions
Shares issued for conversion \| shares	1,323,905
ACELYRIN \| Performance based RSU
Acquisitions
Shares issued for conversion \| shares	146,963
Percentage of performance conditions achieved	100.00%
ACELYRIN \| Performance based RSU \| Merger closes before May 15, 2025
Acquisitions
Number of installments \| installment	2
ACELYRIN \| ACELYRIN Plans
Acquisitions
Common stock reserved for future issuance \| shares	4,712,186

Summary of Significant Accounting Policies and Basis of Presentation (Details)	3 Months Ended
	Mar. 31, 2026 segment
Summary of Significant Accounting Policies and Basis of Presentation
Number of reportable segment	1
Number of operating segment	1

Summary of Significant Accounting Policies and Basis of Presentation

3 Months Ended

Mar. 31, 2026

Summary of Significant Accounting Policies and Basis of Presentation

Summary of Significant Accounting Policies and Basis of Presentation

2.	Summary of Significant Accounting Policies and Basis of Presentation

The significant accounting policies and estimates used in the preparation of the accompanying unaudited condensed consolidated financial statements are described in the Company’s audited consolidated financial statements for the year ended December 31, 2025 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 19, 2026. There have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2026.

Basis of Presentation

The condensed consolidated financial statements and accompanying notes are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the SEC regarding interim financial reporting and do not contain all information that is included in the annual financial statements and notes thereto of the Company.

The Company’s unaudited condensed consolidated financial statements include the accounts of its subsidiaries, and all intercompany transactions were eliminated. The Company’s unaudited condensed consolidated financial statements include the accounts of its subsidiaries ACELYRIN and WH2, LLC after the closing of the ACELYRIN Merger, and the accounts of Merger Sub from its incorporation in January 2025 until the ACELYRIN Merger. WH2, LLC has not had any operations or any balances since the closing of the ACELYRIN Merger.

The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position as of March 31, 2026 and its results of operations and its cash flows for the three months ended March 31, 2026 and 2025. The condensed balance sheet as of December 31, 2025, included in this filing, was derived from audited annual consolidated financial statements but does not include all disclosures required by U.S. GAAP. The results of operations for the three months ended March 31, 2026 and 2025 are not necessarily indicative of the results of operations to be expected for the full year or for any other subsequent interim period.

Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).

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, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period.

On an ongoing basis, the Company evaluates estimates and assumptions, including but not limited to those related to accrued research and development expenses, valuation of acquired in-process research and development (“IPR&D”) intangible assets, revenue recognition, and stock-based compensation expense. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates.

Segment and Geographical Information

The Company operates and manages its business as one reportable and operating segment, which is the business of researching and developing medicines for autoimmune disorders. The chief executive officer, who is the chief operating decision maker (“CODM”), reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. See Note 14 for additional information. All of the Company’s long-lived assets are located in the United States.

Concentration of Credit Risk

Financial instruments which potentially subject the Company to concentration of credit risk consist primarily of cash and cash equivalents, investments in marketable securities, accounts receivable and restricted cash. The Company maintains

bank deposits in federally insured financial institutions and certain of these deposits exceed federally insured limits. To date, the Company has not experienced any losses on its deposits of cash and periodically evaluates the creditworthiness of the financial institutions at which its bank deposits are maintained.

The Company also invests in money market funds, U.S. Treasury obligations, commercial paper, corporate debt obligations, supranational debt obligations, and government development bank obligations, which can be subject to certain credit risks. The Company mitigates credit risk by limiting its exposure to any one issuer and monitoring the ongoing creditworthiness of the financial institutions at which investments are maintained and of the issuers of the marketable securities. To date, the Company has not experienced any loss of principal on its financial instruments.

The Company considers a customer to be significant when revenues from that customer represent 10% or more of total revenues. All of the Company’s revenues are currently earned under its license and collaboration agreement with Kaken. As a result, the Company is subject to customer concentration risk. To date, the Company has not incurred any credit losses in connection with the Kaken Collaboration Agreement.

Risks and Uncertainties

The Company is subject to certain risks and uncertainties, including, but not limited to, changes in any of the following areas that the Company believes could have a material adverse effect on the future financial position or results of operations: the Company’s ability to advance the development of its proprietary precision data analytics platform, timing and ability to advance its product candidates through preclinical and clinical development; costs and timelines associated with the manufacturing of clinical supplies; regulatory approval, market acceptance of, and reimbursement for, any product candidates the Company may develop; performance of third-party vendors; competition from pharmaceutical or other biotechnology companies with greater financial resources or expertise; protection of intellectual property; litigation or claims against the Company based on intellectual property or other factors; and its ability to attract and retain employees necessary to support its growth.

Further, the Company’s business and results of operations may be affected by worldwide economic conditions, which may continue to be impacted by global macroeconomic challenges and uncertainty in the markets, including international trade policies and tariffs, severely diminished liquidity and credit availability, rising inflation and monetary supply shifts, rising interest rates, labor shortages, declines in consumer confidence, declines in economic growth, increases in unemployment rates, recession risks and uncertainty about economic and geopolitical stability. The United States and other countries have imposed and may continue to impose new trade restrictions and export regulations, have levied tariffs and taxes on certain goods, including tariffs targeting pharmaceutical products and related inputs, and could continue to significantly increase tariffs on a broad array of goods. Similarly, the Company’s financial condition and results of operations may continue to be affected by global volatility and general market disruption resulting from geopolitical tensions, such as the ongoing Russia-Ukraine military conflict and the ongoing military conflict involving the U.S., Israel and Iran. In particular, the continued escalation of hostilities in the Middle East, including involving Iran, could further disrupt global energy markets, fuel prices, transportation networks, and supply chains, which may disrupt or otherwise negatively impact the Company’s supply chain and increase its costs. These worldwide economic conditions, global trade policies and geopolitical developments may negatively impact the Company’s business, financial position and results of operations.

Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the JOBS Act, and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and private companies, the Company will adopt the new or revised standard at the time private companies adopt the new or revised standard and will do so until such time that the Company either (i) irrevocably elects to “opt out” of

such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for private companies.

Recently Adopted Accounting Pronouncements

In July 2025, the FASB issued ASU 2025‑05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets (“ASU 2025-05”) which provides a practical expedient and accounting policy election related to estimating expected credit losses for certain receivables and contract assets. The Company adopted ASU 2025‑05 as of January 1, 2026. Adoption of this guidance did not have a material impact on the Company’s consolidated financial statements.

Recently Issued and Not Yet Adopted Accounting Pronouncements

In November 2024, the FASB issued ASU No. 2024-03, Disaggregation of Income Statement Expenses (Topic 220) (“ASU 2024-03”), requiring that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. The amendments of ASU 2024-03 are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The requirements of ASU 2024-03 may be applied either prospectively to financial statements issued for reporting periods after the effective date or retrospectively to any or all prior periods presented in the financial statements. The Company is currently evaluating the impact of adopting ASU 2024-03 on its consolidated financial statements and disclosures.

In December 2025, the FASB issued ASU No. 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements (“ASU 2025-11”), which clarifies the form and content of interim financial statements, adds a comprehensive list of required interim disclosures, and provides a disclosure principle for condensed interim financial statements. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. Early adoption is permitted and, on adoption, can be applied either prospectively or retrospectively to any or all periods presented in the financial statements. The Company is currently evaluating the impact of the new standard on the Company's consolidated financial statements and related disclosures.

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2026

Stock-Based Compensation

Schedule of the Company's option activity


				Weighted-
		Weighted-		Average
		Average		Remaining	Aggregate
		Exercise		Contractual	Intrinsic
	Stock	Price Per		Term	Value
	Options	Share		(in years)	(in thousands)
Outstanding as of December 31, 2025	18,672,626	$	8.56	6.7	$	44,015
Granted	4,459,928	$	26.27
Exercised	(2,177,964)	$	10.68		$	802
Forfeited or expired	(115,429)	$	12.10
Outstanding, vested and expected to vest as of March 31, 2026	20,839,161	$	12.11	7.80	$	11,556
Exercisable as of March 31, 2026	9,695,191	$	10.13	5.90	$	2,098


					Weighted-
			Weighted-		Average
			Average		Remaining		Aggregate
			Exercise		Contractual		Intrinsic
		Stock	Price Per		Term		Value
		Options	Share		(in years)		(in thousands)
Outstanding as of December 31, 2025		1,680,472	$	10.19		8.3	$	—
Granted		—	$	—
Forfeited or expired		(419)	$	10.19
Outstanding, vested and expected to vest as of March 31, 2026		1,680,053	$	10.19		8.1	$	—
Exercisable as of March 31, 2026		—	$	—		—	$	—

Schedule of various significant assumptions used to estimate the fair value of stock options


		Three Months Ended March 31,
		2026		2025
Expected term (in years)		6.04 - 6.06		6.04 - 6.08
Volatility		96.34% - 96.71%		98.84% - 99.18%
Risk-free interest rate		3.81% - 3.92%		4.04% - 4.65%
Dividend yield		0.00%		0.00%

Schedule of activity for the Company's early exercisable shares


				Weighted-
				Average
		Number of		Exercise Price
		Shares		Per Share
Unvested as of December 31, 2025		13,681		$	9.01
Vested		(3,201)		$	9.13
Unvested as of March 31, 2026		10,480		$	8.97

Schedule of estimating the fair value of the stock purchase rights under the ESPP


		Three Months Ended
		March 31, 2026
Expected term (in years)		0.49
Volatility		67.54%
Risk-free interest rate		3.75%
Dividend yield		0.00%

Schedule of unvested RSU activity


				Weighted-
				Average
				Grant Date
		Number of		Fair Value
		Shares		Per Share
Unvested as of December 31, 2025		2,527,377		$	4.01
RSUs granted		877,331		$	25.08
RSUs released		(47,509)		$	5.20
RSUs forfeited		(76,873)		$	5.96
Unvested as of March 31, 2026		3,280,326		$	9.59

Schedule of the stock-based compensation expense

The following table summarizes the stock-based compensation expense recognized in the Company’s condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2026 and 2025 (in thousands):


		Three Months Ended March 31,
		2026			2025
Research and development		$	7,352		$	3,719
General and administrative			4,987			3,276
Total stock-based compensation expense		$	12,339		$	6,995

The following table summarizes stock-based compensation expense recognized in the Company’s condensed consolidated statements of operations and comprehensive loss by award type for the three months ended March 31, 2026 and 2025 (in thousands):


		Three Months Ended March 31,
		2026			2025
Stock options		$	10,463		$	6,803
RSUs			1,560			—
ESPP			316			186
Restricted stock awards			—			6
Total stock-based compensation expense		$	12,339		$	6,995

Fair Value Measurements - Transfers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Fair Value Measurements
Financial Assets Transfer from Level 1 to Level 2	$ 0	$ 0
Financial Assets Transfer from Level 2 to Level 1	0	0
Financial Liabilities Transfer from Level 1 to Level 2	0	0
Financial Liabilities Transfer from Level 2 to Level 1	$ 0	$ 0

Balance Sheet Components - Other Accrued Expenses and Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Balance Sheet Components
Accrued professional services	$ 6,699	$ 4,397
Accrued personnel and related expenses	5,528	17,581
Severance liability		244
Other	361	81
Total other accrued expenses and current liabilities	$ 12,588	$ 22,303

Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2026

Balance Sheet Components

Schedule of other prepaid expenses and current assets

Other prepaid expenses and current assets consisted of the following as of March 31, 2026 and December 31, 2025 (in thousands):


		March 31,			December 31,
		2026			2025
Interest receivable		$	2,231		$	1,343
Prepaid subscriptions			1,963			2,088
Tax receivable			499			740
Prepaid insurance			413			744
Prepaid credit voucher for clinical manufacturing			268			683
Other			659			1,142
Total other prepaid expenses and current assets		$	6,033		$	6,740

Schedule of property and equipment, net

Property and equipment, net consisted of the following as of March 31, 2026 and December 31, 2025 (in thousands):


		Estimated Useful Life		March 31,			December 31,
		(in years)		2026			2025
Leasehold improvements		Shorter of useful life or lease term		$	17,870		$	17,655
Laboratory equipment		5			5,843			5,843
Furniture and fixtures		5			1,709			1,709
Computer equipment		5			896			896
Capitalized software		3			75			75
Total property and equipment, gross					26,393			26,178
Less: Accumulated depreciation and amortization					(8,859)			(7,988)
Total property and equipment, net				$	17,534		$	18,190

Schedule of other accrued expenses and current liabilities

Other accrued expenses and current liabilities consisted of the following as of March 31, 2026 and December 31, 2025 (in thousands):


		March 31,			December 31,
		2026			2025
Accrued professional services		$	6,699		$	4,397
Accrued personnel and related expenses			5,528			17,581
Severance liability			—			244
Other			361			81
Total other accrued expenses and current liabilities		$	12,588		$	22,303

Stock Based Compensation - Valuation of Stock Options - 2024 POP Plans (Details) - 2024 POP - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	May 31, 2024	Mar. 31, 2026
Stock-Based Compensation
Common stock fair value ($ per share)	$ 12.06
Expected term (in years)	6 years
Volatility (%)	122.00%
Risk-free interest rate	4.38%
Share-Based payment award, options, issued in period, fair value		$ 18.0
Performance period		36 months
Maximum
Stock-Based Compensation
Share-Based payment award, award derived service period		2 years 1 month 6 days
Minimum
Stock-Based Compensation
Share-Based payment award, award derived service period		1 year 4 months 24 days

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($)	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Stock-Based Compensation Expense
Stock-based compensation expense recognized	$ 12,339,000	$ 6,995,000
Unrecognized stock-based compensation expense for all stock awards	$ 161,200,000
Period over which unamortized stock-based compensation expense to be recognized	3 years
Non-employee
Stock-Based Compensation Expense
Stock-based compensation expense recognized	$ 300,000	100,000
2024 POP
Stock-Based Compensation Expense
Stock-based compensation expense recognized	1,400,000	2,100,000
Stock options
Stock-Based Compensation Expense
Stock-based compensation expense recognized	10,463,000	6,803,000
RSUs
Stock-Based Compensation Expense
Stock-based compensation expense recognized	1,560,000
ESPP
Stock-Based Compensation Expense
Stock-based compensation expense recognized	316,000	186,000
Restricted stock awards
Stock-Based Compensation Expense
Stock-based compensation expense recognized		6,000
Restricted stock awards \| Non-employee
Stock-Based Compensation Expense
Stock-based compensation expense recognized	0
Research and development
Stock-Based Compensation Expense
Stock-based compensation expense recognized	7,352,000	3,719,000
General and administrative
Stock-Based Compensation Expense
Stock-based compensation expense recognized	$ 4,987,000	$ 3,276,000

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2026
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Acquisition - Assets acquired and liabilities assumed (Details) - ACELYRIN $ in Thousands	May 21, 2025 USD ($)
Assets Acquired
Cash and cash equivalents	$ 49,155
Restricted cash	367
Marketable securities	333,436
Research and development prepaid expenses	958
Prepaid credit voucher for clinical manufacturing	11,376
Other prepaid expenses and current assets	8,081
Restricted cash, non-current	220
Property and equipment	420
Intangible assets	50,959
Operating lease right-of-use assets	4,349
Other assets, non-current	744
Total assets	460,065
Liabilities Assumed
Accounts payable	(6,518)
Research and development accrued expenses	(3,546)
Other accrued expenses and current liabilities	(5,688)
Operating lease liabilities, current	(1,390)
Operating lease liabilities, non-current	(6,238)
Deferred tax liability	(10,701)
Total liabilities	(34,081)
Fair value of net assets	425,984
Purchase consideration	238,077
Gain on bargain purchase	$ 187,907

Stock-Based Compensation - Valuation assumptions of ESPP (Details) - 2024 ESPP	3 Months Ended
	Mar. 31, 2026
Fair value of the stock purchase rights under the ESPP
Expected term (in years)	5 months 26 days
Volatility (%)	67.54%
Risk-free interest rate (%)	3.75%
Dividend yield (%)	0.00%

Commitments and Contingent Liabilities - Components of lease costs and other information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Jan. 31, 2025
Components of lease cost
Operating lease costs	$ 1,299	$ 1,115
Variable lease costs	279	351
Total lease costs	1,578	1,466
Cash payments included in the measurement of operating lease liabilities	$ 2,235	$ 1,468
Weighted-average remaining lease term (years)	6 years 7 months 6 days		6 years 9 months 18 days
Weighted-average incremental borrowing rate	11.60%		11.60%	7.90%

Commitments and Contingent Liabilities

3 Months Ended

Mar. 31, 2026

Commitments and Contingent Liabilities

Commitments and Contingent Liabilities

9.Commitments and Contingent Liabilities

Operating Leases

In August 2022, the Company entered into a lease agreement for 55,000 square feet of office and laboratory space in South San Francisco, California, which commenced in January 2023 and has a contractual termination date in August 2033. The lease agreement includes a renewal option allowing the Company to extend this lease for an additional three years at the prevailing rental rate, which the Company was not reasonably certain to exercise.

In December 2024, the Company entered into a lease agreement for approximately 22,000 square feet of additional office space in South San Francisco, California. The lease has a contractual termination date of December 2026, with the right to extend the lease for an additional two years subject to certain conditions. The Company determined that, for accounting purposes, the commencement date of the lease is in January 2025 and the lease term ends in December 2026, as it was not reasonably certain that the lease would be extended. As of the commencement date, future lease payments totaled $1.9 million and the lease liability was calculated to be $1.8 million, which is equal to the present value of the future lease payments, discounted at an incremental borrowing rate of 7.9%. In April 2026, the Company entered into an amended agreement to extend the lease for an additional two years ending in December 2028, with undiscounted lease payments totaling $2.1 million over this period. The amended agreement has an option to extend the lease for an additional two years subject to certain conditions.

Upon the closing of the ACELYRIN Merger, the Company became the successor to ACELYRIN’s rights under ACELYRIN’s lease and sublease agreements. In January 2023, ACELYRIN entered into a lease agreement to rent approximately 10,012 square feet of office space in Southern California. The term of the lease is 65 months with an option to extend it for an additional three years. Monthly rent payments are approximately $30,500, subject to an annual 3.0% increase. In addition to the base rent, the Company is obligated to pay variable costs related to its share of operating expenses and taxes. In December 2025, the Company entered into an agreement to sublease the entirety of its Southern California leased space through August 24, 2028, the remainder of the lease term. The sublease included the operating lease right-of-use asset and certain property, plant and equipment. Sublease income was immaterial for the three months ended March 31, 2026. In April 2026, the Company delivered a notice of termination to the sublessee, and the sublease was legally terminated in April 2026.

In July 2023, ACELYRIN entered into a lease agreement to rent approximately 22,365 square feet of office space in South San Francisco, California. The term of the lease is 60 months with an option to extend it for an additional five years. Monthly base rent payments are approximately $150,000, subject to an annual 3.5% increase. In addition to the base rent, the Company is obligated to pay variable costs related to its share of operating expenses and taxes. In February 2025,

ACELYRIN entered into an agreement to sublease the entirety of its South San Francisco leased space through October 2029, the remainder of the lease term. The sublease included the operating lease right-of-use asset and certain property, plant and equipment. Sublease income was immaterial for the three months ended March 31, 2026.

The components of lease costs were as follows (in thousands):


		Three Months Ended March 31,
		2026			2025
Operating lease costs		$	1,299		$	1,115
Variable lease costs			279			351
Total lease costs		$	1,578		$	1,466

Supplemental cash flow information related to the operating leases was as follows (in thousands):

Weighted-average remaining lease term and incremental borrowing rate for the operating leases were as follows:


		March 31,		December 31,
		2026		2025
Weighted-average remaining lease term (years)		6.6		6.8
Weighted-average incremental borrowing rate		11.6	%	11.6	%

Future minimum lease payments under non-cancelable leases as of March 31, 2026, were as detailed below (in thousands):


2026 (remainder of the year)	$	6,250
2027		7,648
2028		7,765
2029		7,205
2030		5,848
Thereafter		16,009
Total undiscounted lease payments		50,725
Less: Imputed interest		(15,061)
Total operating lease liabilities	$	35,664

FronThera Contingent Consideration

In March 2021, the Company entered into a stock purchase agreement to acquire FronThera U.S. Holdings, Inc. and its wholly owned subsidiary, FronThera U.S. Pharmaceuticals LLC. (the “FronThera Acquisition”), and the transaction was accounted for as an asset acquisition. Under the stock purchase agreement, the Company is obligated to pay contingent consideration of up to an aggregate of $120.0 million based on the achievement of specified clinical and approval milestones, including receipt of first commercialization approval in the United States or certain other jurisdictions, of up to an aggregate of $70.0 million payable for clinical milestones, and of up to an aggregate of $50.0 million payable for approval milestones, all related to technology acquired under the agreement. In the year ended December 31, 2022, the Company incurred and made a $37.0 million milestone payment for the first administration of envu to a patient enrolled in a Phase 2 clinical trial of envu, which was recorded in research and development expenses in the consolidated statement of operations and comprehensive loss. In July 2024, the Company met a milestone in connection with the first administration of envu to a patient enrolled in a Phase 3 clinical trial of envu and made a $23.0 million milestone payment

in August 2024, which was recorded in research and development expenses in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2024. No additional milestones were achieved or were probable of being achieved as of March 31, 2026.

License and Commercialization Agreement with Pierre Fabre

Upon the closing of the ACELYRIN Merger, the Company became the successor to ACELYRIN’s rights and obligations under the March 25, 2021 license and commercialization agreement with Pierre Fabre Medicament SAS (“Pierre Fabre”), as amended (the “Pierre Fabre Agreement”), through which ACELYRIN received certain exclusive worldwide licenses with the right to sublicense certain patents, know-how and other intellectual property to develop, manufacture, use and commercialize lonigutamab for non-oncology therapeutic indications. The license from Pierre Fabre extends to any product containing lonigutamab (excluding any fragments or derivatives) as its sole active ingredient (each, a “PF Licensed Product”). The Pierre Fabre Agreement prohibits the Company from using the licensed intellectual property in any antibody drug conjugate, multi-specific antibodies or any other derivatives of lonigutamab.

The Company is obligated to (i) make payments of up to $100.5 million upon the achievement of various development and regulatory milestones, (ii) make milestone payments of up to $390.0 million upon the achievement of certain commercial milestones, and (iii) pay tiered royalties in the high single-digit to low-teen percentages to Pierre Fabre on worldwide net sales in a given calendar year. Royalties will be payable for each PF Licensed Product in a given country during a period commencing upon the first commercial sale of such PF Licensed Product in such country and continuing until the latest of (a) 10 years after such first commercial sale, (b) expiration of last-to-expire valid claim in a licensed patent in such country and (c) expiration of regulatory exclusivity for such PF Licensed Product in such country. In the event the Company enters into a sublicense with a third party, the Company must also share with Pierre Fabre a percentage of any revenues from option fees, upfront payments, license maintenance fees, milestone payments or the like generated from the sublicense. Such percentage may be between the high single-digits to the low thirties based on which stage of development of a PF Licensed Product the sublicense relates to.

Unless earlier terminated, the Pierre Fabre Agreement will continue on a PF Licensed Product-by-PF Licensed Product and country-by-country basis until there are no more royalty payments owed to Pierre Fabre on any PF Licensed Product thereunder. Either party may terminate the Pierre Fabre Agreement upon an uncured material breach, or upon the bankruptcy or insolvency of the other party. Pierre Fabre may also terminate the agreement if the Company or any of its affiliates institutes a patent challenge against the licensed patents from Pierre Fabre. The Company may also terminate the Pierre Fabre Agreement with or without cause upon nine months’ prior written notice, so long as there is no ongoing clinical trial for any PF Licensed Product.

No milestones were achieved or were probable of being achieved as of March 31, 2026.

Purchase Commitments

The Company enters into various agreements in the ordinary course of business, such as those with suppliers, clinical research organizations (“CROs”), contract manufacturing organizations (“CMOs”) and clinical trial sites. Upon the closing of the ACELYRIN Merger, the Company became the successor to contracts with non-cancellable commitments under ACELYRIN contracts. The total value of non-cancellable purchase commitments under contracts was $1.5 million as of March 31, 2026. This presentation of non-cancellable purchase commitments does not include any estimates of potential reduction of such liabilities related to mitigation obligations of the counterparties in the event of cancellation under the terms of its engagements.

Legal Contingencies

From time to time, the Company has and may become involved in legal proceedings arising in the ordinary course of business, any or all of which could have a material adverse impact on the Company, including its financial position. The

outcomes of legal proceedings are not within the Company’s complete control and may not be known for prolonged periods of time. The Company records a liability for such matters when it is probable that future losses will be incurred and that such losses can be reasonably estimated. Significant judgment by the Company is required to determine both probability and the estimated amount. Legal costs related to these matters, including attorney fees, are expensed as incurred and are recorded as general and administrative expenses in the consolidated statements of operations and comprehensive loss.

On November 15, 2023, a purported federal securities class action lawsuit was commenced in the United States District Court for the Central District of California. On February 15, 2024, the Court appointed joint lead plaintiffs and lead counsel. An amended complaint was filed on March 26, 2024 (Boukadoum v. Acelyrin, Inc. et al., No. 2:23-cv-09672-FMO-MAA), naming ACELYRIN and then-current and former executive officers and directors as defendants. The complaint alleges that the defendants violated the Exchange Act and Securities Act by misleading investors about the Phase 2b trial of izokibep in hidradenitis suppurativa. The original complaint was filed following ACELYRIN’s announcement of the week 16 results from the Part B portion of such Phase 2b trial. The amended complaint seeks damages and an award of reasonable costs and expenses, including attorneys’ fees, expert fees and other costs, as well as such other and further relief as the court may deem just and proper. On May 3, 2024, the defendants filed their motion to dismiss the amended complaint, which was granted by the court, with leave to amend, in January 2026. On February 5, 2026, the plaintiffs filed a second amended complaint, which seeks damages and an award of reasonable costs and expenses, as well as such other and further relief as the court may deem just and proper. On February 19, 2026, the defendants filed their motion to dismiss the second amended complaint, which remains pending.

It is possible that additional suits will be filed, or allegations made by stockholders, with respect to these same or other matters and also naming the Company and/or its officers and directors as defendants. This lawsuit and any other potential lawsuits are subject to inherent uncertainties, and the actual defense and disposition costs will depend upon many unknown factors. The outcome of this lawsuit is necessarily uncertain. The Company could be forced to expend significant resources in the defense against this and any other related lawsuits and the Company may not prevail. The Company currently is not able to estimate the possible loss to the Company from this lawsuit, as this lawsuit is currently at an early stage, and such amounts could be material to the Company’s financial statements even if the Company prevails in the defense against this lawsuit. The Company cannot be certain how long it may take to resolve this lawsuit or the possible amount of any damages that the Company may be required to pay. As of March 31, 2026, the Company did not consider any payment to be probable or reasonably estimable and had not accrued for any potential liability relating to this lawsuit.

Guarantees and Indemnifications

In the normal course of business, the Company enters into agreements that contain a variety of representations and provide for general indemnification. Its exposure under these agreements is unknown because it involves claims that may be made against the Company in the future. To the extent permitted under Delaware law, the Company has agreed to indemnify its directors and officers for certain events or occurrences while the director or officer is, or was, serving in such capacity. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. As of March 31, 2026 and December 31, 2025, the Company did not have any material indemnification claims that were probable or reasonably possible and consequently has not recorded related liabilities.

Balance Sheet Components - Other Prepaid Expenses and Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Balance Sheet Components [Line Item]
Interest receivable	$ 2,231	$ 1,343
Prepaid subscriptions	1,963	2,088
Tax receivable	499	740
Prepaid insurance	413	744
Prepaid credit voucher for clinical manufacturing	268	683
Other	659	1,142
Total other prepaid expenses and current assets	6,033	$ 6,740
Other prepaid expenses and current assets
Balance Sheet Components [Line Item]
Prepaid credit voucher for clinical manufacturing	300
Other assets, non-current
Balance Sheet Components [Line Item]
Prepaid credit voucher for clinical manufacturing included in other assets, non-current	$ 5,800

Stock-Based Compensation - 2024 Stock Plans (Details)				1 Months Ended		3 Months Ended
Stock-Based Compensation - 2024 Stock Plans (Details)	Jan. 01, 2026 shares	Jun. 27, 2024 USD ($) shares	Jun. 26, 2024 USD ($)	Jun. 30, 2024 shares	May 31, 2024 D $ / shares shares	Mar. 31, 2026 shares	Dec. 31, 2025 shares
Stock-Based Compensation
Common stock reserved for future issuance						35,125,582	31,068,650
2024 POP
Stock-Based Compensation
Common stock reserved for future issuance					1,880,680
2024 POP \| Non-Statutory Option
Stock-Based Compensation
Number of Stock options granted to purchase shares					1,880,680
Grants in period, exercise price \| $ / shares					$ 10.19
Consecutive trading dates \| D					30
Maximum performance condition satisfaction period					6 years
Vesting period					36 months
2024 EIP
Stock-Based Compensation
Common stock reserved for future issuance		7,800,000
Vesting period		4 years
Shares authorized to be added from another plan		6,829,339
Increase in annual percentage		5.00%
Increased number of shares reserved under the plan	5,235,338
Number of shares authorized to grant under the plan		43,888,017
Share based compensation arrangement share based payment award, maximum term		10 years
Percentage of estimated fair market value of common stock (%)		110.00%
Award expiration period		5 years
2024 EIP \| Maximum \| Director \| Executives
Stock-Based Compensation
Maximum grant date fair market value of all awards and all cash compensation paid \| $		$ 1,000,000	$ 750,000
2024 ESPP
Stock-Based Compensation
Common stock reserved for future issuance				650,000
Increase in annual percentage				1.00%
Annual increase in number of shares reserved and available for issuance				1,950,000
Number of shares reserved under 2024	1,047,067
Percentage of shares purchase rate from fair value on offering date that participants pay for shares.				85.00%
Issuance of common stock under the 2024 ESPP (in shares)						0
Automatic increase period (in years)				10 years

Commitments and Contingent Liabilities - Purchase Commitments (Details) $ in Millions	Mar. 31, 2026 USD ($)
Commitments and Contingent Liabilities
Total value of non-cancellable purchase commitments under contracts	$ 1.5

Stockholders' Equity - Common Stock Issued to Executives - Restricted common stock activity (Details) - Restricted common stock	3 Months Ended
	Mar. 31, 2025 $ / shares shares
Number of Shares
Unvested as of beginning of the period (Shares) \| shares	2,583
Vested (Shares) \| shares	(2,583)
Weighted-Average Grant Date Fair Value
Unvested as on beginning of the period ($ per share) \| $ / shares	$ 2.9
Vested ($ per shares) \| $ / shares	$ 2.9

Commitments and Contingent Liabilities - FronThera Contingent Consideration (Details) - FronThera - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2024	Mar. 31, 2021	Dec. 31, 2022	Mar. 31, 2026
FronThera Contingent Consideration
Milestone payment obligation				$ 0.0
Clinical milestones
FronThera Contingent Consideration
Contingent consideration liability		$ 120.0
Milestone payment made	$ 23.0	70.0	$ 37.0
Approval milestones \| Maximum
FronThera Contingent Consideration
Milestone payment made		$ 50.0

Related Party Transactions

3 Months Ended

Mar. 31, 2026

Related Party Transactions

Related Party Transactions

8.	Related Party Transactions

Foresite Labs Services Agreement

Foresite Labs, LLC (“Foresite Labs”) is an affiliate of Foresite Capital Management, a stockholder of the Company. In January 2021, the Company entered into a services agreement with Foresite Labs, which was amended and restated in August 2021 and in December 2023, and expires in December 2026, unless terminated earlier by the parties. Thereafter, on each anniversary of the effective date, the agreement will automatically renew for an additional one-year term, unless terminated earlier by the parties. Foresite Labs provides services to assist the Company in exploring specified immunology genetic targets. The Company recognized $0.1 million and $0.3 million as research and development expenses under the services agreement for the three months ended March 31, 2026 and 2025, respectively. There were no accrued expenses under the services agreement as of March 31, 2026 or December 31, 2025.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

+ Details

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2026	May 05, 2026
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2026
Document Fiscal Year Focus	2026
Document Transition Report	false
Entity File Number	001-42143
Entity Registrant Name	Alumis Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	86-1771129
Entity Address, Address Line One	280 East Grand Avenue
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	231-6625
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	ALMS
Security Exchange Name	NASDAQ
Entity Central Index Key	0001847367
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q1
Amendment Flag	false
Voting common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		123,432,072
Non-voting common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		4,059,908

Commitments and Contingent Liabilities - Operating Leases (Details)	1 Months Ended
	Dec. 31, 2024 ft²	Jul. 31, 2023 USD ($) ft²	Jan. 31, 2023 USD ($) ft²	Apr. 30, 2026 USD ($)	Mar. 31, 2026 USD ($)	Dec. 31, 2025	Jan. 31, 2025 USD ($)	Aug. 31, 2022 ft²
Operating Leases
Lease space \| ft²	22,000							55,000
Future lease payments					$ 50,725,000		$ 1,900,000
Lease liability					$ 35,664,000		$ 1,800,000
Weighted-average incremental borrowing rate					11.60%	11.60%	7.90%
Renewal term								3 years
Lessee, Operating Lease, Lease Not yet Commenced, Existence of Option to Extend [true false]	true
Lease not yet commenced, renewal term	2 years
Subsequent Events
Operating Leases
Future lease payments				$ 2,100,000
Renewal term				2 years
ACELYRIN
Operating Leases
Lease space \| ft²		22,365	10,012
Term of lease		60 months	65 months
Renewal term		5 years	3 years
Monthly rent payments		$ 150,000	$ 30,500
Percentage increase in monthly rent payments		3.50%	3.00%

Stock-Based Compensation

3 Months Ended

Mar. 31, 2026

Stock-Based Compensation

Stock-Based Compensation

11.	Stock-Based Compensation

2021 Stock Plan

In February 2021, the Company adopted the 2021 Stock Plan (the “2021 Plan”), which provided for stock awards to eligible employees, directors and consultants of the Company. Awards issuable under the 2021 Plan included incentive stock options (“ISOs”), non-statutory stock options (“NSOs”), RSUs and stock grants. Subsequent to the adoption of the 2024 Equity Incentive Plan (the “2024 EIP”) in June 2024, described below, no additional shares were available for issuance under the 2021 Plan, and any stock options granted under the 2021 Plan that were subsequently forfeited would be made available for issuance under the 2024 EIP.

The terms of the 2021 Plan permit option holders to exercise stock options before their stock options are vested. The shares of common stock granted upon early exercise that have not yet vested are subject to repurchase by the Company in the event of termination of the holder’s continuous status as a service provider, at the price paid by the holder.

2024 Performance Option Plan

In May 2024, the Company’s board of directors adopted, and its stockholders approved, the 2024 Performance Option Plan (the “2024 POP”). The Company reserved 1,880,680 shares of common stock issuable under the 2024 POP. The 2024 POP permits grants of ISOs, NSOs and restricted stock awards to the Company’s employees, directors and consultants.

In May 2024, the Company granted NSOs to employees to purchase 1,880,680 shares of common stock at an exercise price of $10.19 under the 2024 POP. Stock options generally vest on the date when the Company meets certain common stock public market price specified targets after the end of the IPO lock-up period, subject to continuous service through each respective vest date. The price targets are calculated based on the volume weighted average price per share over 30 consecutive trading dates, in accordance with the grant terms. The unvested awards will expire if it is determined that the vesting conditions have not been met during the applicable six-year performance period. The service condition includes monthly vesting over 36 months from the vesting commencement date and the employee’s continuous service with the Company through each such monthly vesting date. The terms of the 2024 POP permit option holders to exercise stock options before their stock options are vested, if the market condition has been met.

2024 Equity Incentive Plan

In June 2024, the Company’s board of directors adopted, and its stockholders approved, the 2024 EIP, which became effective on June 27, 2024, upon execution of the underwriting agreement related to the Company’s IPO. The Company reserved 7,800,000 new shares of common stock for issuance under the 2024 EIP. In addition, up to 6,829,339 shares subject to awards under the 2021 Plan that terminate, expire, or lapse for any reason without the delivery of shares, or are reacquired or withheld (or not issued) to satisfy a tax withholding obligation or the purchase or exercise price, were authorized to be added to the 2024 EIP. The 2024 EIP also provides that the number of shares initially reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2025 through January 1, 2034, by an amount equal to 5% of the outstanding number of shares of the Company’s common stock as of the last day of the immediately preceding fiscal year, or such lesser number of shares as determined by the board of directors prior to the applicable January 1. Pursuant to this evergreen provision, the Company increased the number of shares reserved under the 2024 EIP by 5,235,338 on January 1, 2026. No more than 43,888,017 shares of common stock may be issued under the 2024 EIP.

The 2024 EIP allows the Company to grant equity awards to its officers, employees, directors and consultants. The 2024 EIP provides for the grant of ISOs, NSOs, restricted stock awards, RSUs, stock appreciation rights, performance awards and other stock-based awards. Stock options under the 2024 EIP may be granted for periods of up to 10 years at exercise prices no less than the fair market value of common stock on the date of grant; provided, however, that the exercise price of an ISO granted to a 10% stockholder may not be less than 110% of the fair market value of the shares on the date of grant and such option may not be exercisable after the expiration of five years from the date of grant. Stock options and RSUs granted under the 2024 EIP generally vest over four years. The grant date fair market value of all awards made under the 2024 EIP and all cash compensation paid by the Company to any non-employee director for services as a director in any fiscal year may not exceed $750,000, increased to $1,000,000 in the fiscal year of their initial service as a non-employee director. The terms of the 2024 EIP do not permit option holders to exercise stock options before their stock options are vested.

ACELYRIN Plans

Pursuant to the Merger Agreement, the Company assumed certain stock options, RSUs and performance RSUs outstanding under the ACELYRIN, Inc. 2020 Stock Option and Grant Plan, as amended (the “ACELYRIN 2020 Plan”), the

ValenzaBio, Inc. Stock Plan (the “ValenzaBio Plan”) and the ACELYRIN, Inc. 2023 Equity Incentive Plan (the “ACELYRIN 2023 Plan” and, together with the ACELYRIN 2020 Plan and the ValenzaBio Plan, the “ACELYRIN Plans”). In connection with the closing of the ACELYRIN Merger, the Company also assumed the ACELYRIN 2023 Plan, which, as modified in connection with such assumption, permits equity awards to be issued to the extent permissible under applicable law and Nasdaq listing rules.

Stock options that were outstanding under the ACELYRIN Plans immediately prior to the Closing Date were assumed by the Company and converted into stock options to purchase the Company’s common stock. RSUs that were outstanding and unvested immediately prior to the Closing Date were assumed by the Company and converted into the Company’s RSU awards. Performance RSUs outstanding and unvested immediately prior to the Closing Date were converted into the Company’s RSU awards subject only to a service vesting condition.

Stock Option Activity

The following table summarizes the Company’s stock option activity, excluding under the 2024 POP, for the three months ended March 31, 2026 and includes early exercised shares as part of stock options exercised:


				Weighted-
		Weighted-		Average
		Average		Remaining	Aggregate
		Exercise		Contractual	Intrinsic
	Stock	Price Per		Term	Value
	Options	Share		(in years)	(in thousands)
Outstanding as of December 31, 2025	18,672,626	$	8.56	6.7	$	44,015
Granted	4,459,928	$	26.27
Exercised	(2,177,964)	$	10.68		$	802
Forfeited or expired	(115,429)	$	12.10
Outstanding, vested and expected to vest as of March 31, 2026	20,839,161	$	12.11	7.80	$	11,556
Exercisable as of March 31, 2026	9,695,191	$	10.13	5.90	$	2,098

Total exercisable shares of 9,695,191 as of March 31, 2026 included 1,675,362 unvested shares that were early exercisable under the 2021 Plan. The total fair value of stock options vested during the three months ended March 31, 2026 and 2025 was $7.4 million and $3.4 million, respectively.

The following table summarizes the Company’s stock option activity under the 2024 POP for the three months ended March 31, 2026:


					Weighted-
			Weighted-		Average
			Average		Remaining		Aggregate
			Exercise		Contractual		Intrinsic
		Stock	Price Per		Term		Value
		Options	Share		(in years)		(in thousands)
Outstanding as of December 31, 2025		1,680,472	$	10.19		8.3	$	—
Granted		—	$	—
Forfeited or expired		(419)	$	10.19
Outstanding, vested and expected to vest as of March 31, 2026		1,680,053	$	10.19		8.1	$	—
Exercisable as of March 31, 2026		—	$	—		—	$	—

Valuation of Stock Options Granted under Non-Performance Plans

The weighted-average grant date fair value of stock options granted for the three months ended March 31, 2026 and 2025

was $20.80 and $4.10 per stock option, respectively.

The fair value of stock options granted for the three months ended March 31, 2026 and 2025 was estimated using the Black-Scholes option pricing model with the following assumptions:


		Three Months Ended March 31,
		2026		2025
Expected term (in years)		6.04 - 6.06		6.04 - 6.08
Volatility		96.34% - 96.71%		98.84% - 99.18%
Risk-free interest rate		3.81% - 3.92%		4.04% - 4.65%
Dividend yield		0.00%		0.00%

Expected Term

The expected term represents the weighted-average period the stock options are expected to remain outstanding and is based on the stock options’ vesting terms and contractual terms, as the Company did not have sufficient historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior.

Expected Volatility

The expected stock price volatility assumption was determined by examining the historical volatilities for industry peers, as the Company did not have sufficient trading history of its common stock. The Company will continue to use industry peers in determining historical stock price volatility until sufficient historical data of its common stock becomes available.

Risk-Free Interest Rate

The risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the Company’s stock options.

Dividends

The Company has not paid any cash dividends on common stock since inception and does not anticipate paying any dividends in the foreseeable future. Consequently, an expected dividend yield of zero was used.

Valuation of Stock Options Granted under the 2024 POP

Stock options granted under the 2024 POP vest based on service, market and performance conditions (the occurrence of the IPO or a change of control) and are classified as equity financial instruments. At the grant date, the fair value of stock options granted under the 2024 POP was estimated using a Monte Carlo simulation model, which uses a distribution of potential outcomes on a monthly basis over the vesting period prioritizing the most reliable information available. The assumptions utilized in the calculation were based on the achievement of certain stock price thresholds, including the Company’s expected common stock price, expected volatility, risk-free rate and expected term. The Company used the following assumptions to estimate the fair value at the grant date in May 2024: common stock fair value of $12.06, vesting term of 6.0 years, volatility of 122.00%, and risk-free rate of 4.38%. The estimates of fair value are uncertain and changes in any of the estimated inputs could have resulted in significant adjustments to the fair value.

The Company’s estimated fair value of stock options issued under the 2024 POP of $18.0 million is recognized using graded vesting from July 1, 2024, the closing of the IPO, when the performance condition was met, over the longer of (i) the explicit service period of the service condition of 36 months or (ii) the derived service period between 1.4 years to 2.1 years, as determined for each graded vesting tranche.

Early Exercise of Employee Stock Options

Proceeds from the early exercise of stock options are recorded as share repurchase liability, and as shares vest are recognized to additional paid-in capital in the consolidated balance sheets. As of March 31, 2026 and December 31, 2025, share repurchase liability related to unvested shares was $0.1 million and $0.1 million, respectively, and was classified as share repurchase liability in the condensed consolidated balance sheets.

The following table summarizes the Company’s early exercised shares activity for the three months ended March 31, 2026:


				Weighted-
				Average
		Number of		Exercise Price
		Shares		Per Share
Unvested as of December 31, 2025		13,681		$	9.01
Vested		(3,201)		$	9.13
Unvested as of March 31, 2026		10,480		$	8.97

2024 Employee Stock Purchase Plan

In June 2024, the Company’s board of directors adopted, and its stockholders approved, the 2024 ESPP, which became effective on June 28, 2024, upon execution of the underwriting agreement related to the Company’s IPO. The Company initially reserved 650,000 shares of common stock for issuance under the 2024 ESPP. The number of shares of common stock reserved for issuance under the 2024 ESPP will be automatically increased each year for ten calendar years beginning on January 1, 2025 through January 1, 2034, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on the last day of the calendar month before the date of the automatic increase, and (ii) 1,950,000 shares; provided that before the date of any such increase, the board of directors may determine that such increase will be less than the amount in (i) and (ii) above. Pursuant to this evergreen provision, the Company increased the number of shares reserved under the 2024 ESPP by 1,047,067 on January 1, 2026. The 2024 ESPP allows an eligible employee to purchase shares of common stock at an amount equal to 85% of the lower of the fair market value of the Company’s common stock at the beginning of the offering period or at each applicable purchase date during an offering period as established by the board of directors. The first purchase period commenced on January 24, 2025 and ended on May 20, 2025. During the three months ended March 31, 2026, no shares of common stock were purchased under the 2024 ESPP.

The following table summarizes the Black-Scholes option pricing model used in estimating the fair value of the stock purchase rights under the 2024 ESPP for the three months ended March 31, 2026:


		Three Months Ended
		March 31, 2026
Expected term (in years)		0.49
Volatility		67.54%
Risk-free interest rate		3.75%
Dividend yield		0.00%

Restricted Stock Units

The following table summarizes the Company’s unvested RSUs activity for the three months ended March 31, 2026:


				Weighted-
				Average
				Grant Date
		Number of		Fair Value
		Shares		Per Share
Unvested as of December 31, 2025		2,527,377		$	4.01
RSUs granted		877,331		$	25.08
RSUs released		(47,509)		$	5.20
RSUs forfeited		(76,873)		$	5.96
Unvested as of March 31, 2026		3,280,326		$	9.59

Stock-Based Compensation Expense


		Three Months Ended March 31,
		2026			2025
Research and development		$	7,352		$	3,719
General and administrative			4,987			3,276
Total stock-based compensation expense		$	12,339		$	6,995


		Three Months Ended March 31,
		2026			2025
Stock options		$	10,463		$	6,803
RSUs			1,560			—
ESPP			316			186
Restricted stock awards			—			6
Total stock-based compensation expense		$	12,339		$	6,995

Stock-based compensation expense related to non-employee awards was $0.3 million and $0.1 million for the three months ended March 31, 2026 and 2025, respectively. Stock-based compensation expense related to the 2024 POP was $1.4 million and $2.1 million for the three months ended March 31, 2026 and 2025, respectively.

As of March 31, 2026, unrecognized stock-based compensation expense for all stock awards was $161.2 million, which the Company expects to recognize over a weighted-average period of 3.0 years.

Commitments and Contingent Liabilities - Schedule of future minimum lease payments under non-cancelable operating leases (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Jan. 31, 2025
Schedule of future minimum lease payments under non-cancelable operating leases
2026 (remainder of the year)	$ 6,250
2027	7,648
2028	7,765
2029	7,205
2030	5,848
Thereafter	16,009
Total undiscounted lease payments	50,725	$ 1,900
Less: Imputed interest	(15,061)
Total operating lease liabilities	$ 35,664	$ 1,800

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025
Pay vs Performance Disclosure
Net Income (Loss)	$ (93,053)	$ (98,963)

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479168/946-830-55-10

Reference 2: 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

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476153/220-40-55-21

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476153/220-40-55-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-28

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-4

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 480
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479857/480-10-S50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 480
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479887/480-10-S45-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 480
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3A
-Subparagraph (24)(d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480244/480-10-S99-3A

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 105
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 9
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479343/105-10-65-9

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 17
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480336/718-10-65-17

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-6

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-9

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 60
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476176/805-60-65-1

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 323
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (g)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478666/740-323-65-2

Reference 19: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482765/220-10-50-6

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-3

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-1

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480175/815-40-65-1

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-8

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-11

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-11

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479105/946-220-45-7

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(9))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 32: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(1)(d))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 34: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 38: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 39: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 40: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 41: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 42: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 43: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-60B

Reference 44: http://www.xbrl.org/2003/role/disclosureRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483499/205-20-50-7

Reference 45: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 46: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-1A

Reference 47: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-1B

Reference 48: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 65
-Paragraph 4
-Subparagraph (f)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481538/470-20-65-4

Reference 49: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

Marketable Securities (Details) - USD ($) $ in Thousands	3 Months Ended
Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Marketable Securities
Marketable securities, current - Amortized Cost Basis	$ 459,413		$ 218,643
Marketable securities, current - Gross Unrealized Gains	31		188
Marketable securities, current - Gross Unrealized Losses	(386)
Marketable securities, current - Fair Value	459,058		218,831
Marketable securities, non-current - Amortized Cost Basis	46,715
Marketable securities, non-current - Gross Unrealized Losses	(112)
Marketable securities, non-current - Fair Value	46,603
Amortized Cost Basis	506,128
Gross Unrealized Gains	31
Gross Unrealized Losses	(498)
Fair Value	505,661
Allowance for expected credit losses	0	$ 0
U.S. Treasury obligations
Marketable Securities
Marketable securities, current - Amortized Cost Basis	309,024		148,352
Marketable securities, current - Gross Unrealized Gains	21		129
Marketable securities, current - Gross Unrealized Losses	(214)
Marketable securities, current - Fair Value	308,831		148,481
Marketable securities, non-current - Amortized Cost Basis	30,175
Marketable securities, non-current - Gross Unrealized Losses	(82)
Marketable securities, non-current - Fair Value	30,093
Corporate debt obligations
Marketable Securities
Marketable securities, current - Amortized Cost Basis	85,951		30,720
Marketable securities, current - Gross Unrealized Gains	3		24
Marketable securities, current - Gross Unrealized Losses	(105)
Marketable securities, current - Fair Value	85,849		30,744
Marketable securities, non-current - Amortized Cost Basis	16,540
Marketable securities, non-current - Gross Unrealized Losses	(30)
Marketable securities, non-current - Fair Value	16,510
Commercial paper
Marketable Securities
Marketable securities, current - Amortized Cost Basis	52,466		27,652
Marketable securities, current - Gross Unrealized Gains	3		20
Marketable securities, current - Gross Unrealized Losses	(67)
Marketable securities, current - Fair Value	52,402		27,672
Supranational debt obligations
Marketable Securities
Marketable securities, current - Amortized Cost Basis	7,969		7,913
Marketable securities, current - Gross Unrealized Gains	2		9
Marketable securities, current - Fair Value	7,971		7,922
Government development bank obligations
Marketable Securities
Marketable securities, current - Amortized Cost Basis	4,003		4,006
Marketable securities, current - Gross Unrealized Gains	2		6
Marketable securities, current - Fair Value	$ 4,005		$ 4,012

Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Property and Equipment, net
Total property and equipment, gross	$ 26,393		$ 26,178
Less: Accumulated depreciation and amortization	(8,859)		(7,988)
Total property and equipment, net	17,534		$ 18,190
Depreciation and amortization	$ 900	$ 800
Leasehold improvements
Property and Equipment, net
Property, Plant, and Equipment, Useful Life, Term, Description [Extensible Enumeration]	us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember		us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember
Total property and equipment, gross	$ 17,870		$ 17,655
Laboratory equipment
Property and Equipment, net
Estimated Useful Life (in years)	5 years		5 years
Total property and equipment, gross	$ 5,843		$ 5,843
Furniture and fixtures
Property and Equipment, net
Estimated Useful Life (in years)	5 years		5 years
Total property and equipment, gross	$ 1,709		$ 1,709
Computer equipment
Property and Equipment, net
Estimated Useful Life (in years)	5 years		5 years
Total property and equipment, gross	$ 896		$ 896
Capitalized software
Property and Equipment, net
Estimated Useful Life (in years)	3 years		3 years
Total property and equipment, gross	$ 75		$ 75

Employee Benefit Plans

3 Months Ended

Mar. 31, 2026

Employee Benefit Plans

Employee Benefit Plans

12.Employee Benefit Plans

The Company sponsors a qualified 401(k) defined contribution plan covering eligible employees. Participants may contribute a portion of their annual compensation limited to a maximum annual amount set by the Internal Revenue Service. In November 2025, the Company’s board of directors approved a Company match of 100% of participating

employee’s deferral contribution up to 3% of eligible compensation and a 50% match of participating employees’ deferral contribution from 3% to 5% of eligible compensation, effective from January 1, 2026. The Company contributed $0.9 million to the 401(k) plan during the three months ended March 31, 2026.

Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2026

Stockholders' Equity

Schedule of common stock reserved for issuance


		March 31,		December 31,
		2026		2025
Stock options issued and outstanding		22,519,214		20,353,098
RSUs issued and outstanding		3,280,326		2,527,377
Shares available for grant under the 2024 Equity Incentive Plan		1,008,617		597,112
Shares available for grant under the 2024 Employee Stock Purchase Plan		1,852,401		805,334
Shares available for grant under the ACELYRIN, Inc. 2023 Equity Incentive Plan		6,264,397		6,585,521
Shares available for grant under the 2024 Performance Option Plan		200,627		200,208
Total		35,125,582		31,068,650

Schedule of summarizes the activity for the company's restricted common stock


				Weighted-
				Average
		Number of		Grant Date
		Shares		Fair Value
Unvested as of December 31, 2024		2,583		$	2.90
Vested		(2,583)		$	2.90
Unvested as of March 31, 2025		—		$	—

Fair Value Measurements

3 Months Ended

Mar. 31, 2026

Fair Value Measurements

Fair Value Measurements

4.	Fair Value Measurements

The Company discloses and recognizes the fair value of its assets and liabilities using a hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The guidance establishes three levels of the fair value hierarchy as follows:

Level 1—Quoted prices in active markets for identical assets or liabilities.

Level 2—Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The Company recognizes transfers into and out of levels within the fair value hierarchy in the period in which the actual event or change in circumstances that caused the transfer occurs.

The Company’s financial instruments consist of Level 1 and Level 2 financial instruments. Changes in the ability to observe valuation inputs may result in a reclassification of levels of certain securities within the fair value hierarchy.

Level 1 financial instruments are comprised of money market funds and U.S. Treasury obligations. Level 2 financial instruments are comprised of U.S. Treasury obligations, corporate debt obligations, commercial paper, supranational debt obligations and government development bank obligations. Marketable securities are considered Level 2 when their fair values are determined using inputs that are observable in the market or can be derived principally from or corroborated by observable market data such as pricing for similar securities, recently executed transactions, cash flow models with yield curves, and benchmark securities.

The following tables present the Company’s fair value hierarchy for financial assets measured at fair value on a recurring basis as of March 31, 2026 and December 31, 2025 (in thousands):


	March 31, 2026
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents
Money market funds	$	58,736	$	—	$	—	$	58,736
Marketable securities, current
U.S. Treasury obligations		207,241		101,590		—		308,831
Corporate debt obligations		—		85,849		—		85,849
Commercial paper		—		52,402		—		52,402
Supranational debt obligations		—		7,971		—		7,971
Government development bank obligations		—		4,005		—		4,005
Marketable securities, non-current
U.S. Treasury obligations		30,093		—		—		30,093
Corporate debt obligations		—		16,510		—		16,510
Total assets	$	296,070	$	268,327	$	—	$	564,397


		December 31, 2025
		Level 1			Level 2			Level 3			Total
Assets:
Cash equivalents
Money market funds		$	81,729		$	—		$	—		$	81,729
U.S. Treasury obligations			3,971			—			—			3,971
Marketable securities, current
U.S. Treasury obligations			110,809			37,673			—			148,482
Corporate debt obligations			—			30,743			—			30,743
Commercial paper			—			27,672			—			27,672
Supranational debt obligations			—			7,922			—			7,922
Government development bank obligations			—			4,012			—			4,012
Total assets		$	196,509		$	108,022		$	—		$	304,531

The Company did not hold Level 3 financial instruments and there were no transfers between Level 1 and Level 2 categories during the three months ended March 31, 2026 and 2025.

- 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

Stock-Based Compensation - RSUs activity (Details) - RSUs	3 Months Ended
	Mar. 31, 2026 $ / shares shares
Number of Shares
Unvested as of beginning of the period (Shares) \| shares	2,527,377
RSUs granted (Shares) \| shares	877,331
RSUs released (Shares) \| shares	(47,509)
RSUs forfeited (Shares) \| shares	(76,873)
Unvested as of ending of the period (Shares) \| shares	3,280,326
Weighted-Average Grant Date Fair Value Per Share
Unvested as on beginning of the period ($ per share) \| $ / shares	$ 4.01
RSUs granted ($ per shares) \| $ / shares	25.08
RSUs released ($ per shares) \| $ / shares	5.2
RSUs forfeited ($ per shares) \| $ / shares	5.96
Unvested as of ending of the period ($ per share) \| $ / shares	$ 9.59

Commitments and Contingent Liabilities - License and Commercialization Agreement (Details) - License and commercialization agreement - Pierre Fabre - USD ($) $ in Millions	Mar. 25, 2021	Mar. 31, 2026
License and Commercialization Agreements
Maximum milestone payment upon achievement of development and regulatory milestones	$ 100.5
Maximum milestone payment upon achievement of certain commercial milestones	$ 390.0
Royalty Payment, expiration period from first commercial sale of licensed product	10 years
Prior written notice period for termination of agreement	9 months
Milestone payment obligation		$ 0.0

Employee Benefit Plans (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
Employee Benefit Plans (Details) - USD ($) $ in Millions	Nov. 30, 2025	Mar. 31, 2026
Employee Benefit Plans
Employer contribution under the plan		$ 0.9
Deferral contribution up to three percent
Employee Benefit Plans
Employer match (as a percentage)	100.00%
Eligible compensation (as a percentage)	3.00%
Deferral contribution between three percent and five percent
Employee Benefit Plans
Employer match (as a percentage)	50.00%
Deferral contribution between three percent and five percent \| Minimum
Employee Benefit Plans
Eligible compensation (as a percentage)	3.00%
Deferral contribution between three percent and five percent \| Maximum
Employee Benefit Plans
Eligible compensation (as a percentage)	5.00%

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (k)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (j)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (j)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (j)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (j)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (c)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (c)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-7

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (m)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

+ Details

Stockholders' Equity - Narratives (Details)	3 Months Ended
Stockholders' Equity - Narratives (Details)	Mar. 31, 2026 $ / shares shares	Dec. 31, 2025 $ / shares shares
Stockholders' Equity (Deficit)
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, par or stated value per share \| $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Number of days prior written notice	61 days
Voting common stock
Stockholders' Equity (Deficit)
Common stock, shares authorized	492,815,092	492,815,092
Common stock, par or stated value per share \| $ / shares	$ 0.0001	$ 0.0001
Common stock, shares issued	123,169,838	99,084,365
Common stock, shares outstanding	123,169,838	99,084,365
Conversion ratio	1
Maximum beneficial ownership percent after conversion	4.99
Non-voting common stock
Stockholders' Equity (Deficit)
Common stock, shares authorized	7,184,908	7,184,908
Common stock, par or stated value per share \| $ / shares	$ 0.0001	$ 0.0001
Common stock, shares issued	4,059,908	5,622,408
Common stock, shares outstanding	4,059,908	5,622,408

Stockholders' Equity - Stock reserved for issuance (Details) - shares	Mar. 31, 2026	Dec. 31, 2025
Stockholders' Equity (Deficit)
Common stock reserved for future issuance	35,125,582	31,068,650
Employee Stock Option
Stockholders' Equity (Deficit)
Common stock reserved for future issuance	22,519,214	20,353,098
RSUs issued and outstanding
Stockholders' Equity (Deficit)
Common stock reserved for future issuance	3,280,326	2,527,377
Shares available for grant \| Shares available for grant under the 2024 Equity Incentive Plan
Stockholders' Equity (Deficit)
Common stock reserved for future issuance	1,008,617	597,112
Shares available for grant \| Shares available for grant under the 2024 Employee Stock Purchase Plan
Stockholders' Equity (Deficit)
Common stock reserved for future issuance	1,852,401	805,334
Shares available for grant \| Shares available for grant under the ACELYRIN, Inc. 2023 Equity Incentive Plan
Stockholders' Equity (Deficit)
Common stock reserved for future issuance	6,264,397	6,585,521
Shares available for grant \| Shares available for grant under the 2024 Performance Option Plan
Stockholders' Equity (Deficit)
Common stock reserved for future issuance	200,627	200,208

- Definition

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

+ References

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

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

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 480
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479857/480-10-S50-1

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 6: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483014/272-10-45-3

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482987/272-10-50-1

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-18

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

+ Details

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Current assets:
Cash and cash equivalents	$ 63,885	$ 89,670
Restricted cash	86	82
Marketable securities, current	459,058	218,831
Research and development prepaid expenses	3,345	2,909
Other prepaid expenses and current assets	6,033	6,740
Total current assets	532,407	318,232
Restricted cash, non-current	1,302	1,301
Marketable securities, non-current	46,603
Property and equipment, net	17,534	18,190
Intangible assets	50,959	50,959
Operating lease right-of-use assets, net	15,952	16,971
Other assets, non-current	6,831	6,287
Total assets	671,588	411,940
Current liabilities:
Accounts payable	11,587	10,106
Research and development accrued expenses	35,959	34,781
Other accrued expenses and current liabilities	12,588	22,303
Deferred revenue, current	6,328	1,458
Operating lease liabilities, current	4,442	4,670
Total current liabilities	70,904	73,318
Operating lease liabilities, non-current	31,222	32,244
Deferred tax liability	2,140	2,140
Share repurchase liability	94	123
Deferred revenue, non-current		2,611
Other liabilities, non-current	207	207
Total liabilities	104,567	110,643
Commitments and contingencies (Note 9)
Stockholders' equity:
Preferred stock, $0.0001 par value; 50,000,000 shares authorized, zero shares issued and outstanding as of March 31, 2026 and December 31, 2025
Additional paid-in capital	1,562,405	1,202,975
Accumulated other comprehensive income (loss)	(467)	188
Accumulated deficit	(994,929)	(901,876)
Total stockholders' equity	567,021	301,297
Total liabilities and stockholders' equity	671,588	411,940
Voting common stock
Stockholders' equity:
Common Stock	$ 12	9
Non-voting common stock
Stockholders' equity:
Common Stock		$ 1

Stock-Based Compensation - 2021 Stock Plan (Details)	Jun. 30, 2024 shares
2021 Stock Plan
Stock-Based Compensation
Number of shares available for issuance under the plan	0

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

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

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480483/718-10-35-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(02)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(03)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Net Loss Per Share Attributable to Common Stockholders - Potentially dilutive securities excluded from computation (Details) - shares	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Net Income (Loss) Per Share Attributable to Common Stockholders
Potential dilutive shares excluded from computation of diluted net loss per share	26,065,910	13,506,570
Employee Stock Option
Net Income (Loss) Per Share Attributable to Common Stockholders
Potential dilutive shares excluded from computation of diluted net loss per share	22,519,214	13,245,589
RSUs issued and outstanding
Net Income (Loss) Per Share Attributable to Common Stockholders
Potential dilutive shares excluded from computation of diluted net loss per share	3,280,326
Common stock issuable under the 2024 ESPP
Net Income (Loss) Per Share Attributable to Common Stockholders
Potential dilutive shares excluded from computation of diluted net loss per share	255,890	158,031
Early exercised stock options and unvested restricted common stock
Net Income (Loss) Per Share Attributable to Common Stockholders
Potential dilutive shares excluded from computation of diluted net loss per share	10,480	102,950

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Revenue:
Total revenue	$ 1,741	$ 17,389
Operating expenses:
Research and development expenses, including related party expenses of $66 and $262 for the three months ended March 31, 2026 and 2025, respectively	81,540	96,622
General and administrative expenses	18,610	22,295
Total operating expenses	100,150	118,917
Loss from operations	(98,409)	(101,528)
Other income (expense):
Interest income	5,349	2,609
Other income (expenses), net	7	(44)
Total other income (expense), net	5,356	2,565
Net loss	(93,053)	(98,963)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities, net	(655)	(48)
Total comprehensive loss	$ (93,708)	$ (99,011)
Net loss per share attributable to common stockholders, basic	$ (0.74)	$ (1.82)
Net loss per share attributable to common stockholders, diluted	$ (0.74)	$ (1.82)
Weighted-average shares of common stock outstanding, basic	125,050,645	54,280,264
Weighted-average shares of common stock outstanding, diluted	125,050,645	54,280,264
License
Revenue:
Total revenue		$ 17,389
Collaboration
Revenue:
Total revenue	$ 1,741

Revenue

3 Months Ended

Mar. 31, 2026

Revenue

Revenue

Kaken Collaboration Agreement

On March 25, 2025 (the “Effective Date”), the Company entered into the Kaken Collaboration Agreement. Under the terms of the Kaken Collaboration Agreement, the Company granted to Kaken an exclusive right to develop, manufacture and commercialize envu for dermatology indications in Japan, with options to expand the license, subject to opt-in payments and certain cost-sharing obligations on the part of Kaken, to include rheumatological and gastrointestinal diseases.

Pursuant to the terms of the Kaken Collaboration Agreement, the Company is responsible for the global development of envu in the dermatology field, and Kaken is responsible for the clinical development, regulatory approvals and commercialization of envu in Japan in dermatology and other indications for which Kaken has exercised its option. Kaken is required to use commercially reasonable efforts to conduct all subsequent development, manufacture, and commercialization activities. The Kaken Collaboration Agreement further provides that the Company will retain rights to envu in all other indications and geographies.

In March 2025, Kaken made an upfront, non-refundable payment of $20.0 million to the Company. In addition, Kaken will pay the Company an aggregate of $20.0 million towards global development costs for envu in the dermatology field through the end of 2026 and thereafter will pay a specified share of development costs applicable to the dermatology field, and for any field for which Kaken exercises its option, subject to Kaken's right to opt out of cost-sharing in certain indications in specified circumstances. In addition, Kaken would pay the Company up to an aggregate of $36.0 million upon the achievement of regulatory milestones and upon Kaken’s exercise of its field expansion options for the rheumatology and gastrointestinal fields. In addition, the Company is entitled to receive aggregate payments of up to ¥15.5 billion upon the achievement of commercial milestones, plus tiered royalties at percentages ranging from the low double digits into the twenties on aggregate net sales of envu in Japan.

The Company evaluated the Kaken Collaboration Agreement and concluded it was within the scope of ASC 606. As of the Effective Date, the Company identified four performance obligations: (1) license to develop, manufacture and commercialize envu (the “License Obligation”), (2) development services that support the global development of envu (the “Development Services Obligation”), (3) the manufacture of the clinical supply in Japan (the “Manufacturing Services Obligation”) and (4) a material right related to the option for rheumatology disease (the “Material Right Obligation”). The License Obligation was considered functional intellectual property and distinct from other promises under the contract, as Kaken can benefit from the license on its own or together with other readily available resources. The Development Services Obligation and Manufacturing Services Obligation were considered distinct as Kaken could benefit from both of these separately with the license transferred by the Company at the inception of the agreement. The option in the rheumatology field contained a material right because its exercise does not require payment of a fee that is commensurate with the value of the additional license. No material right was assigned to the gastrointestinal field since its estimated fair value did not

exceed the exercise price of the option.

The transaction price includes the upfront license fee of $20.0 million, the global development cost reimbursement of $20.0 million in the dermatology field through the end of 2026, the estimated global development cost reimbursement in the dermatology field after 2026 of $1.5 million and an immaterial amount of variable consideration related to the Manufacturing Services Obligation. The Company determined that any variable consideration related to development and regulatory milestones was deemed to be fully constrained at inception and therefore excluded from the initial transaction price due to the high degree of uncertainty and risk associated with these potential payments, and the Company could not assert that it was probable that a significant reversal in the amount of cumulative revenue recognized would not occur.

The Company developed the estimated standalone selling prices for the License Obligation and Material Right Obligation primarily based on the probability-weighted value of expected future revenues associated with each underlying license. In developing such estimates, the Company applied judgment in determining the forecasted revenue, taking into consideration the applicable market conditions, the probability of success, and the time needed to develop each indication for which the license relates. The Company developed the estimated standalone selling price for the development services and clinical supply primarily based on the resources to be committed to perform the service.

At inception of the contract, the Company allocated $17.4 million to the License Obligation, $20.8 million to the Development Services Obligation, $3.3 million to the Material Right Obligation and an immaterial amount to the Manufacturing Services Obligation. The License Obligation was satisfied in March 2025 upon transfer of the license to Kaken. For the Development Services Obligation, the Company recognizes revenue over time as Kaken consumes the benefit of such services as they are being performed. The Company measures proportional performance over time for the Development Services Obligation by using an input method based on cost incurred relative to the total estimated cost of the obligation on a quarterly basis. The Company re-evaluates the transaction price as uncertain events are resolved or other changes in circumstances occur as of the end of each reporting period.

The Company recognized revenue of zero and $17.4 million for the three months ended March 31, 2026 and 2025, respectively, related to the License Obligation and $1.7 million and zero for the three months ended March 31, 2026 and 2025, respectively, related to the Development Services Obligation and Manufacturing Services Obligation. As of March 31, 2026, collaboration revenue receivable was less than $1 thousand, deferred revenue, current was $6.3 million and deferred revenue, non-current was zero. As of December 31, 2025, collaboration revenue receivable was less than $0.1 million, deferred revenue, current was $1.5 million and deferred revenue, non-current was $2.6 million. Revenue recognized during the period that was included in deferred revenue at the beginning of the period was $1.5 million and zero for the three months ended March 31, 2026 and 2025, respectively. The aggregate estimated amount of transaction price that was unsatisfied as of March 31, 2026 was $15.8 million, of which, $12.5 million related to the Development Services Obligation that is expected to be recognized through 2028 as the Company performs its services towards the global development of envu in the dermatology field. The remaining $3.3 million estimated amount of transaction price that was unsatisfied as of March 31, 2026 related to the Material Right Obligation and is deferred until the option is exercised or expires.

Tenet Medicines Purchase Agreement

In January 2024, ACELYRIN entered into an asset purchase agreement (“Purchase Agreement”) with Tenet Medicines, Inc. (“Tenet”). In consideration for the assets and other rights Tenet received under the Purchase Agreement, ACELYRIN is entitled to receive development, regulatory and commercial milestone payments of up to $157.5 million in the aggregate based on the achievement of specified milestones, royalties on worldwide net sales, and payments on sublicense income. On December 31, 2025, Climb Bio, Inc. (“Climb Bio”), the parent company of Tenet, filed a complaint in Delaware Superior Court seeking a declaratory judgment that budoprutug is not a “Product” under the Purchase Agreement, and therefore Climb Bio does not owe milestone or royalty payments to the Company under the Purchase Agreement. In January 2026, the Company issued a notice of material breach to Climb Bio for failing to timely pay a $3.0 million development milestone. The Company disputes Climb Bio’s interpretation and intends to seek recovery of the $3.0 million

development milestone, as well as any other future milestone or royalty payments, through litigation. The matter remains pending.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-9

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-10

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-15

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-13

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org/606/tableOfContent

+ Details

Marketable Securities

3 Months Ended

Mar. 31, 2026

Marketable Securities

Marketable Securities

5.	Marketable Securities

Marketable securities, which are classified as available-for-sale, consisted of the following as of March 31, 2026 and December 31, 2025 (in thousands):


		March 31, 2026
				Gross		Gross
		Amortized Cost		Unrealized		Unrealized		Fair
		Basis		Gains		Losses		Value
Marketable securities, current:
U.S. Treasury obligations		$	309,024	$	21	$	(214)	$	308,831
Corporate debt obligations			85,951		3		(105)		85,849
Commercial paper			52,466		3		(67)		52,402
Supranational debt obligations			7,969		2		—		7,971
Government development bank obligations			4,003		2		—		4,005
Total marketable securities, current			459,413		31		(386)		459,058
Marketable securities, non-current:
U.S. Treasury obligations			30,175		—		(82)		30,093
Corporate debt obligations			16,540		—		(30)		16,510
Total marketable securities, non-current			46,715		—		(112)		46,603
Total marketable securities		$	506,128	$	31	$	(498)	$	505,661


		December 31, 2025
				Gross		Gross
		Amortized Cost		Unrealized		Unrealized		Fair
		Basis		Gains		Losses		Value
Marketable securities, current:
U.S. Treasury obligations		$	148,352	$	129	$	—	$	148,481
Corporate debt obligations			30,720		24		—		30,744
Commercial paper			27,652		20		—		27,672
Supranational debt obligations			7,913		9		—		7,922
Government development bank obligations			4,006		6		—		4,012
Total marketable securities		$	218,643	$	188	$	—	$	218,831

Marketable securities classified as current as of March 31, 2026 and December 31, 2025 had contractual maturities of one year or less from the purchase date. Marketable securities classified as non-current as of March 31, 2026 had contractual maturities of greater than one year but less than two years.

As of March 31, 2026 and December 31, 2025, no significant facts or circumstances were present to indicate a deterioration in the creditworthiness of the issuers of the marketable securities, and the Company has no requirement or intention to sell these securities before maturity or recovery of their amortized cost basis. The Company considered the current and expected future economic and market conditions and determined that its marketable securities were not significantly impacted. For all marketable securities with a fair value less than its amortized cost basis, the Company determined the decline in fair value below amortized cost basis to be immaterial and non-credit related, and therefore no allowance for expected credit losses was recorded for the three months ended March 31, 2026 and 2025.

Segment Reporting

3 Months Ended

Mar. 31, 2026

Segment Reporting

Segment Reporting

14.	Segment Reporting

For purposes of evaluating performance and allocating resources, the Company’s CODM, its Chief Executive Officer, regularly reviews consolidated net loss as reported in the Company’s consolidated statements of operations and comprehensive loss as compared to budget. The measure of segment assets is reported in the consolidated balance sheets as total consolidated assets.

In addition to the significant expense categories included within consolidated net loss presented in the Company’s condensed consolidated statements of operations and comprehensive loss, see below for disaggregated amounts that comprise research and development expenses for the three months ended March 31, 2026 and 2025 (in thousands):


		Three Months Ended March 31,
		2026			2025
Revenue:
License revenue		$	—		$	17,389
Collaboration revenue			1,741			—
Total revenue			1,741			17,389
Operating expenses:
Research and development expenses
External costs
CROs, CMOs and clinical trials			40,928			65,072
Professional consulting services			6,804			6,403
Other research and development costs			2,370			2,296
Internal costs
Personnel-related costs			26,065			17,659
Facilities and overhead costs			5,373			5,192
Total research and development expense			81,540			96,622
General and administrative expenses			18,610			22,295
Total operating expenses			100,150			118,917
Loss from operations			(98,409)			(101,528)
Total other income (expense), net			5,356			2,565
Net loss before income taxes			(93,053)			(98,963)
Income tax benefit			—			—
Net loss		$	(93,053)		$	(98,963)

- 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
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-21

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-21

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-31

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-15

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-42

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482964/270-10-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (ee)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 11: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 12: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 54
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-54

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 14: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 54
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-54

Reference 15: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 16: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 54
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-54

Reference 17: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-34

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26C

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26B

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-40

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/280/tableOfContent

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-41

+ Details

Stock-Based Compensation - Valuation of Stock Options - Non-Performance Plans (Details) - Stock options - Non-Performance Plans - $ / shares	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Stock-Based Compensation
Weighted-average grant date fair value of options granted ($ per share)	$ 20.8	$ 4.1
Minimum Volatility (%)	96.34%	98.84%
Maximum Volatility (%)	96.71%	99.18%
Minimum Risk-free interest rate (%)	3.81%	4.04%
Maximum Risk-free interest rate (%)	3.92%	4.65%
Dividend yield (%)	0.00%	0.00%
Minimum
Stock-Based Compensation
Expected term (in years)	6 years 14 days	6 years 14 days
Maximum
Stock-Based Compensation
Expected term (in years)	6 years 21 days	6 years 29 days

Acquisition - Purchase price consideration (Details) - ACELYRIN $ / shares in Units, $ in Thousands	May 21, 2025 USD ($) $ / shares shares
Acquisitions
Implied shares of common stock issued to holders of ACELYRIN common stock \| shares	48,653,549
Closing price per share of common stock as of Closing Date \| $ / shares	$ 4.78
Consideration transferred for share exchange	$ 232,564
Fair value of replacement awards attributable to pre-combination services	5,513
Total purchase price consideration	$ 238,077

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482573/350-20-50-4

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-8

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-47

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-5

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (f)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-2

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (f)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-3

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-4A

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-4

Reference 22: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-4A

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-4A

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-4

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 32: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 37: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 38: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 39: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 40: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 41: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 42: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

+ Details

Segment Reporting (Tables)

3 Months Ended

Mar. 31, 2026

Segment Reporting

Schedule of statements of operations for segment including significant segment expenses


		Three Months Ended March 31,
		2026			2025
Revenue:
License revenue		$	—		$	17,389
Collaboration revenue			1,741			—
Total revenue			1,741			17,389
Operating expenses:
Research and development expenses
External costs
CROs, CMOs and clinical trials			40,928			65,072
Professional consulting services			6,804			6,403
Other research and development costs			2,370			2,296
Internal costs
Personnel-related costs			26,065			17,659
Facilities and overhead costs			5,373			5,192
Total research and development expense			81,540			96,622
General and administrative expenses			18,610			22,295
Total operating expenses			100,150			118,917
Loss from operations			(98,409)			(101,528)
Total other income (expense), net			5,356			2,565
Net loss before income taxes			(93,053)			(98,963)
Income tax benefit			—			—
Net loss		$	(93,053)		$	(98,963)

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Stock option plans excluding the 2024 POP
Stock Options
Stock options outstanding at beginning of the period (shares)	18,672,626
Granted (shares)	4,459,928
Exercised (shares)	(2,177,964)
Forfeited or expired (shares)	(115,429)
Stock options outstanding, vested and expected to vest at end of the period (shares)	20,839,161		18,672,626
Exercisable at end of the period (shares)	9,695,191
Weighted- Average Exercise Price Per Share
Weighted-average exercise price, Outstanding at beginning of the period ($ per shares)	$ 8.56
Weighted-average exercise price, Granted ($ per shares)	26.27
Weighted-average exercise price, Exercised ($ per shares)	10.68
Weighted-average exercise price, Forfeited or expired ($ per shares)	12.1
Weighted-average exercise price, Outstanding, vested and expected to vest at end of the period ($ per shares)	12.11		$ 8.56
Exercisable at end of the period ($ per shares)	$ 10.13
Weighted- Average Remaining Contractual Term
Weighted-average remaining contractual term, Outstanding, vested and expected to vest (in years)	7 years 9 months 18 days		6 years 8 months 12 days
Weighted-average remaining contractual term, Exercisable at end of the period (in years)	5 years 10 months 24 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding at beginning of the period	$ 44,015
Aggregate Intrinsic Value, exercised	802
Aggregate Intrinsic Values, Outstanding, vested and expected to vest at the end of period	11,556		$ 44,015
Aggregate Intrinsic Values, Exercisable at the end of period	2,098
Vested, fair value	$ 7,400	$ 3,400
2021 Plan
Aggregate Intrinsic Value
Unvested and early exercisable shares	1,675,362
2024 POP
Stock Options
Stock options outstanding at beginning of the period (shares)	1,680,472
Forfeited or expired (shares)	(419)
Stock options outstanding, vested and expected to vest at end of the period (shares)	1,680,053		1,680,472
Weighted- Average Exercise Price Per Share
Weighted-average exercise price, Outstanding at beginning of the period ($ per shares)	$ 10.19
Weighted-average exercise price, Forfeited or expired ($ per shares)	10.19
Weighted-average exercise price, Outstanding, vested and expected to vest at end of the period ($ per shares)	$ 10.19		$ 10.19
Weighted- Average Remaining Contractual Term
Weighted-average remaining contractual term, Outstanding, vested and expected to vest (in years)	8 years 1 month 6 days		8 years 3 months 18 days

Acquisition

3 Months Ended

Mar. 31, 2026

Acquisition

Acquisition

3.	Acquisition

ACELYRIN Merger

The Company completed its acquisition of ACELYRIN on May 21, 2025 (the “Closing Date”) and accounted for the transaction as an acquisition under ASC Topic 805, Business Combinations. ACELYRIN was a late-stage biopharma company focused on identifying, acquiring, and accelerating the development and commercialization of transformative medicines. ACELYRIN’s portfolio consisted of lonigutamab, a subcutaneously delivered, monoclonal antibody targeting IGF-1R for the potential treatment of Thyroid Eye Disease (“TED”). The ACELYRIN Merger strengthened the Company’s balance sheet and its cash position and added the lonigutamab product candidate to the Company’s development portfolio as of the Closing Date. The ACELYRIN Merger was accounted for as a business combination with the Company being treated as the accounting acquirer.

As of the Closing Date, the Company (i) issued 48,653,549 shares of its common stock in exchange for ACELYRIN’s issued and outstanding common stock shares and paid cash for fractional shares, (ii) assumed ACELYRIN’s stock options with an exercise price of $18.00 or less outstanding and unexercised immediately prior to the Closing Date, which were exercisable into 4,712,186 shares of the Company’s common stock, (iii) assumed ACELYRIN’s restricted stock units (“RSUs”) outstanding and unvested immediately prior to the Closing Date, which were converted into 1,323,905 of the Company’s RSUs, and (iv) assumed ACELYRIN’s performance RSUs outstanding and unvested immediately prior to the Closing Date, which were converted into 146,963 of the Company’s RSUs subject only to a service vesting condition.

Outstanding shares, stock options, RSUs and performance RSUs were exchanged at the exchange ratio of 0.4814 shares of the Company’s common stock for each share of ACELYRIN’s common stock (the “Exchange Ratio”). ACELYRIN’s outstanding and unexercised stock options with exercise prices more than $18.00 were cancelled. Exercise prices for the assumed stock options were determined as the product of the original exercise prices multiplied by the reciprocal of the Exchange Ratio. Converted ACELYRIN stock options and RSUs continue to vest in accordance with their original terms. Performance RSUs were deemed to have 100% satisfied their performance conditions and will vest in two equal installments on May 15 of calendar years 2026 and 2027, subject to the holder of the converted performance RSUs remaining in service with the Company or any of its subsidiaries on such date.

The purchase price consideration consisted of the Company’s shares of common stock issued as of the Closing Date and the additional stock-based compensation related to the fair value of replacement awards attributable to pre-combination services, and was calculated as follows (in thousands, except share and per share amounts):


Implied shares of common stock issued to holders of ACELYRIN common stock		48,653,549
Closing price per share of common stock as of Closing Date	$	4.78
Consideration transferred for share exchange	$	232,564
Fair value of replacement awards attributable to pre-combination services	$	5,513
Total purchase price consideration	$	238,077

The following table presents the final purchase price allocation of the fair value of the net assets acquired and liabilities assumed as of the Closing Date (in thousands):


Assets Acquired
Cash and cash equivalents	$	49,155
Restricted cash		367
Marketable securities		333,436
Research and development prepaid expenses		958
Prepaid credit voucher for clinical manufacturing		11,376
Other prepaid expenses and current assets		8,081
Restricted cash, non-current		220
Property and equipment		420
Intangible assets		50,959
Operating lease right-of-use assets		4,349
Other assets, non-current		744
Total assets	$	460,065
Liabilities Assumed
Accounts payable	$	(6,518)
Research and development accrued expenses		(3,546)
Other accrued expenses and current liabilities		(5,688)
Operating lease liabilities, current		(1,390)
Operating lease liabilities, non-current		(6,238)
Deferred tax liability		(10,701)
Total liabilities		(34,081)
Fair value of net assets	$	425,984
Purchase consideration		238,077
Gain on bargain purchase	$	187,907

Intangible assets consist of an acquired IPR&D intangible asset related to the lonigutamab product candidate that was in development as of the Closing Date. The acquired IPR&D intangible asset was initially recognized at a fair value of $51.0

million, determined using the multi-period excess earnings method, which reflected the present value of projected incremental after-tax cash flows attributable to the asset as of the Closing Date. The valuation utilized a discount rate of 24.0% representing management’s best estimate of a market participant's after-tax weighted average cost of capital. Projected future cash flows were based on significant estimates, including estimated revenues, costs and probabilities of achieving technical and regulatory milestones, among other factors. The acquired IPR&D intangible asset is classified as an indefinite-lived intangible asset and, accordingly, is not amortized but is subject to annual impairment testing, or more frequently if events or changes in circumstances indicate that the asset may be impaired.

As of March 31, 2026, the Company evaluated its acquired IPR&D intangible asset for indicators of impairment and concluded that no such indicators were present. Subsequent to March 31, 2026, the Company completed its strategic review of the lonigutamab program and decided to explore strategic alternatives for the program. The outcome of this evaluation could represent an event or change in circumstances that may require the Company to perform an interim impairment assessment of the acquired IPR&D intangible asset.

The Company acquired a prepaid credit voucher for clinical manufacturing issued by one of ACELYRIN’s contract manufacturers that will be applied towards payments of clinical product manufacturing invoices issued by the vendor. The remaining balance of $11.4 million as of the Closing Date was not adjusted from its carrying amount as its fair value approximated its carrying value as of this date.

The Company acquired two operating leases and a sublease. Refer to Note 9 for additional details. The Company estimated the fair value of lease liabilities as the present value of the remaining lease payments, as if the acquired leases were new leases of the acquirer as of the Closing Date. The Company measured the right-of-use asset at the same amount as the lease liability as adjusted to reflect favorable or unfavorable terms of the lease when compared with market terms. As ACELYRIN entered into a sublease in February 2025, these sublease terms were considered at market terms. As of the Closing Date, the fair value of operating lease liabilities, current, increased by $0.2 million and the fair value of operating lease liabilities, non-current, increased by $0.5 million. As of the Closing Date, the fair value of operating lease right-of-use assets, net, decreased by $0.1 million.

Because the fair value of the identifiable assets acquired and liabilities assumed exceeded the fair value of the purchase consideration transferred, the Company recorded a gain on bargain purchase of $187.9 million as of the Closing Date. Consequently, the Company reassessed the recognition and measurement of identifiable assets acquired and liabilities assumed in accordance with ASC 805-30-25-4 and concluded that all acquired assets and assumed liabilities were recognized and that the valuation procedures and resulting measures were appropriate. Gain on bargain purchase primarily relates to the market value of ACELYRIN’s common stock trading below the carrying value of net assets and the Exchange Ratio being fixed at the time the Merger Agreement was signed and not adjusted for subsequent changes in the market price of the Company’s common stock. Gain on bargain purchase was recognized as other income in the consolidated statements of operations and comprehensive loss for the year ended December 31, 2025. The Company recognized a deferred tax liability of $10.7 million related to the acquired IPR&D intangible asset as of the Closing Date.

The Company also has additional severance related obligations under the Merger Agreement that are separate from the assets and liabilities acquired. In accordance with the ACELYRIN severance plan, ACELYRIN employees terminated without cause within 12 months of the Closing Date are entitled to receive severance benefits, including acceleration of their outstanding equity awards and extension of their outstanding stock options exercise periods of up to 12 months post-termination. The Company estimated total cash severance obligation, including related taxes, of $11.9 million, which it expected to pay within 12 months from the Closing Date based on agreed termination dates with employees. Severance obligation was recorded to expense over the remaining employment period for notified employees. The Company recognized $6.5 million as general and administrative expenses and $5.4 million as research and development expenses related to severance expenses during the year ended December 31, 2025. The Company substantially paid in full the severance liability by December 31, 2025. The Company estimated stock-based compensation expense of $13.1 million related to the accelerated vesting and exercise term modification for severed employees, which was fully recognized during the year ended December 31, 2025. The Company recognized ACELYRIN Merger transaction costs of $7.7 million in

general and administrative expenses in the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2025.

Following the Closing Date, the operating results of ACELYRIN have been included in the Company’s consolidated financial statements.

The ACELYRIN Merger is intended to be a reorganization under Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”) Section 368(a). The Merger Agreement outlines the “plan of reorganization” within the meaning of the regulations issued under Internal Revenue Code Section 368(a) and the ACELYRIN Merger is intended to qualify as a tax-free reorganization for U.S. federal and state income tax purposes.

- Definition

The entire disclosure for business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-8

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-38

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 46
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-46

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 43
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-43

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 45
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-45

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 29
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-29

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 29
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-29

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-5

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (f)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-3

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-4

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-4

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 40
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479326/805-40-45-1

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/805-30/tableOfContent

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/805-20/tableOfContent

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-7

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-5

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/805-10/tableOfContent

+ Details

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2026 USD ($)
CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
Issuance of common stock in public offering, underwriting discounts, commissions and offering costs	$ 21,260

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Beginning balance at Dec. 31, 2024	$ 5	$ 918,610	$ 40	$ (658,551)	$ 260,104
Beginning balance (in shares) at Dec. 31, 2024	54,407,327
Stockholders' equity
Vesting of early exercised stock options		2			2
Vesting of restricted shares of common stock		224			224
Stock-based compensation expense		6,995			6,995
Other comprehensive income (loss), net			(48)		(48)
Net loss				(98,963)	(98,963)
Ending balance at Mar. 31, 2025	$ 5	925,831	(8)	(757,514)	168,314
Ending balance (in shares) at Mar. 31, 2025	54,407,327
Beginning balance at Dec. 31, 2025	$ 10	1,202,975	188	(901,876)	301,297
Beginning balance (in shares) at Dec. 31, 2025	104,706,773
Stockholders' equity
Issuance of common stock in public offering, net of underwriting discounts, commissions and offering costs of $21,260	$ 2	323,797			323,799
Issuance of common stock in public offering, net of underwriting discounts, commissions and offering costs of $21,260 (in shares)	20,297,500
Issuance of common stock upon exercise of stock options		23,265			23,265
Issuance of common stock upon exercise of stock options (in shares)	2,177,964
Issuance of common stock upon vesting of restricted stock units (in shares)	47,509
Vesting of early exercised stock options		29			29
Stock-based compensation expense		12,339			12,339
Other comprehensive income (loss), net			(655)		(655)
Net loss				(93,053)	(93,053)
Ending balance at Mar. 31, 2026	$ 12	$ 1,562,405	$ (467)	$ (994,929)	$ 567,021
Ending balance (in shares) at Mar. 31, 2026	127,229,746

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2026	Dec. 31, 2025
Preferred stock, par or stated value per share	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Voting common stock
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	492,815,092	492,815,092
Common stock, shares issued	123,169,838	99,084,365
Common stock, shares outstanding	123,169,838	99,084,365
Non-voting common stock
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	7,184,908	7,184,908
Common stock, shares issued	4,059,908	5,622,408
Common stock, shares outstanding	4,059,908	5,622,408

Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2026

Marketable Securities

Schedule Of marketable securities

Marketable securities, which are classified as available-for-sale, consisted of the following as of March 31, 2026 and December 31, 2025 (in thousands):


		March 31, 2026
				Gross		Gross
		Amortized Cost		Unrealized		Unrealized		Fair
		Basis		Gains		Losses		Value
Marketable securities, current:
U.S. Treasury obligations		$	309,024	$	21	$	(214)	$	308,831
Corporate debt obligations			85,951		3		(105)		85,849
Commercial paper			52,466		3		(67)		52,402
Supranational debt obligations			7,969		2		—		7,971
Government development bank obligations			4,003		2		—		4,005
Total marketable securities, current			459,413		31		(386)		459,058
Marketable securities, non-current:
U.S. Treasury obligations			30,175		—		(82)		30,093
Corporate debt obligations			16,540		—		(30)		16,510
Total marketable securities, non-current			46,715		—		(112)		46,603
Total marketable securities		$	506,128	$	31	$	(498)	$	505,661


		December 31, 2025
				Gross		Gross
		Amortized Cost		Unrealized		Unrealized		Fair
		Basis		Gains		Losses		Value
Marketable securities, current:
U.S. Treasury obligations		$	148,352	$	129	$	—	$	148,481
Corporate debt obligations			30,720		24		—		30,744
Commercial paper			27,652		20		—		27,672
Supranational debt obligations			7,913		9		—		7,922
Government development bank obligations			4,006		6		—		4,012
Total marketable securities		$	218,643	$	188	$	—	$	218,831

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

+ Details

Acquisition (Tables)

3 Months Ended

Mar. 31, 2026

Acquisition

Schedule of purchase price and allocation


Implied shares of common stock issued to holders of ACELYRIN common stock		48,653,549
Closing price per share of common stock as of Closing Date	$	4.78
Consideration transferred for share exchange	$	232,564
Fair value of replacement awards attributable to pre-combination services	$	5,513
Total purchase price consideration	$	238,077

The following table presents the final purchase price allocation of the fair value of the net assets acquired and liabilities assumed as of the Closing Date (in thousands):


Assets Acquired
Cash and cash equivalents	$	49,155
Restricted cash		367
Marketable securities		333,436
Research and development prepaid expenses		958
Prepaid credit voucher for clinical manufacturing		11,376
Other prepaid expenses and current assets		8,081
Restricted cash, non-current		220
Property and equipment		420
Intangible assets		50,959
Operating lease right-of-use assets		4,349
Other assets, non-current		744
Total assets	$	460,065
Liabilities Assumed
Accounts payable	$	(6,518)
Research and development accrued expenses		(3,546)
Other accrued expenses and current liabilities		(5,688)
Operating lease liabilities, current		(1,390)
Operating lease liabilities, non-current		(6,238)
Deferred tax liability		(10,701)
Total liabilities		(34,081)
Fair value of net assets	$	425,984
Purchase consideration		238,077
Gain on bargain purchase	$	187,907

Stockholders' Equity

3 Months Ended

Mar. 31, 2026

Stockholders' Equity

Stockholders' Equity

10.	Stockholders’ Equity

As of March 31, 2026, the Company was authorized to issue up to 50,000,000 shares of preferred stock, 492,815,092 shares of voting common stock and 7,184,908 shares of non-voting common stock, all with par values of $0.0001 per share. As of March 31, 2026, there were no shares of preferred stock issued or outstanding, 123,169,838 shares of voting common stock issued and outstanding and 4,059,908 shares of non-voting common stock issued and outstanding.

The holders of voting and non-voting common stock have the same rights except that non-voting common stock does not have voting rights, except as may be required by law. Each holder of non-voting common stock has a right to convert each share of non-voting common stock to one share of voting common stock subject to the following limitations. At any time

following the Company’s registration of any class of equity securities under the Exchange Act, the holders of shares of non-voting common stock may not convert a number of shares of non-voting common stock into shares of voting common stock in excess of that number of shares of non-voting common stock which would cause the holder thereof to beneficially own (for purposes of Section 13(d) of the Exchange Act), in excess of 4.99% of the total number of issued and outstanding shares of voting common stock. Such maximum percentage may be increased or decreased to such other percentage as any holder of outstanding shares of non-voting common stock may designate in writing (in the case of an increase upon 61 days’ prior written notice).

Common stock reserved for issuance consisted of the following as of March 31, 2026 and December 31, 2025:


		March 31,		December 31,
		2026		2025
Stock options issued and outstanding		22,519,214		20,353,098
RSUs issued and outstanding		3,280,326		2,527,377
Shares available for grant under the 2024 Equity Incentive Plan		1,008,617		597,112
Shares available for grant under the 2024 Employee Stock Purchase Plan		1,852,401		805,334
Shares available for grant under the ACELYRIN, Inc. 2023 Equity Incentive Plan		6,264,397		6,585,521
Shares available for grant under the 2024 Performance Option Plan		200,627		200,208
Total		35,125,582		31,068,650

Common Stock Issued to Executives

In February 2021, the Company issued 100,532 shares of restricted common stock to two executives at a purchase price of $0.94 per share. The shares vested over a four-year period with a one-year cliff vesting. While the shares were unvested, the holders had voting and dividends rights and the Company had the right to repurchase unvested shares of common stock at the price paid by the holder in the event of termination of the holder’s continuous status as a service provider. The Company estimated the fair value of the restricted stock awards based on the fair value of common stock at the grant dates. The expense was recognized ratably over the vesting terms. The Company recognized zero and less than $0.1 million of stock-based compensation expense for the three months ended March 31, 2026 and 2025.

The following table summarizes the activity for the Company’s restricted common stock for the three months ended March 31, 2025:


				Weighted-
				Average
		Number of		Grant Date
		Shares		Fair Value
Unvested as of December 31, 2024		2,583		$	2.90
Vested		(2,583)		$	2.90
Unvested as of March 31, 2025		—		$	—

- Definition

The entire disclosure for equity.

+ 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 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478448/946-505-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-6

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-18

+ Details

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2026

Fair Value Measurements

Schedule of fair value of assets

The following tables present the Company’s fair value hierarchy for financial assets measured at fair value on a recurring basis as of March 31, 2026 and December 31, 2025 (in thousands):


	March 31, 2026
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents
Money market funds	$	58,736	$	—	$	—	$	58,736
Marketable securities, current
U.S. Treasury obligations		207,241		101,590		—		308,831
Corporate debt obligations		—		85,849		—		85,849
Commercial paper		—		52,402		—		52,402
Supranational debt obligations		—		7,971		—		7,971
Government development bank obligations		—		4,005		—		4,005
Marketable securities, non-current
U.S. Treasury obligations		30,093		—		—		30,093
Corporate debt obligations		—		16,510		—		16,510
Total assets	$	296,070	$	268,327	$	—	$	564,397


		December 31, 2025
		Level 1			Level 2			Level 3			Total
Assets:
Cash equivalents
Money market funds		$	81,729		$	—		$	—		$	81,729
U.S. Treasury obligations			3,971			—			—			3,971
Marketable securities, current
U.S. Treasury obligations			110,809			37,673			—			148,482
Corporate debt obligations			—			30,743			—			30,743
Commercial paper			—			27,672			—			27,672
Supranational debt obligations			—			7,922			—			7,922
Government development bank obligations			—			4,012			—			4,012
Total assets		$	196,509		$	108,022		$	—		$	304,531

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Research and development expenses	$ 81,540	$ 96,622
Related party
Research and development expenses	$ 66	$ 262

Net Loss Per Share Attributable to Common Stockholders (Tables)

3 Months Ended

Mar. 31, 2026

Net Loss Per Share Attributable to Common Stockholders

Schedule of computation of the basic and diluted net loss per share

The following table presents the computation of the basic and diluted net loss per share attributable to common stockholders for the three months ended March 31, 2026 and 2025 (in thousands, except share and per share amounts):


		Three Months Ended March 31,
		2026			2025
Numerator:
Net loss		$	(93,053)		$	(98,963)
Denominator:
Weighted-average shares of common stock outstanding			125,062,435			54,407,327
Less: Weighted-average shares of common stock subject to repurchase			(11,790)			(127,063)
Weighted-average shares of common stock outstanding, basic and diluted			125,050,645			54,280,264
Net loss per share attributable to common stockholders, basic and diluted		$	(0.74)		$	(1.82)

Schedule of outstanding potentially dilutive securities were excluded from computation of diluted net loss per share


		March 31,		March 31,
		2026		2025
Stock options issued and outstanding		22,519,214		13,245,589
RSUs issued and outstanding		3,280,326		—
Common stock issuable under the 2024 ESPP		255,890		158,031
Early exercised stock options and unvested restricted common stock		10,480		102,950
Total		26,065,910		13,506,570

Stockholders' Equity - Common Stock Issued to Executives - Narrative (Details)	1 Months Ended	3 Months Ended
	Feb. 28, 2021 item $ / shares shares	Mar. 31, 2026 USD ($)	Mar. 31, 2025 USD ($)
Stockholders' Equity (Deficit)
Stock-based compensation expense recognized		$ 12,339,000	$ 6,995,000
Executives
Stockholders' Equity (Deficit)
Stock-based compensation expense recognized		300,000	100,000
Restricted common stock
Stockholders' Equity (Deficit)
Stock-based compensation expense recognized			6,000
Restricted common stock \| Executives
Stockholders' Equity (Deficit)
Number of shares issued under restricted stock award \| shares	100,532
Number of executives to whom restricted stock are issued \| item	2
Purchase price per share ($ per share) \| $ / shares	$ 0.94
Vested period	4 years
Cliff vesting period (years)	1 year
Stock-based compensation expense recognized		$ 0
Restricted common stock \| Executives \| Maximum
Stockholders' Equity (Deficit)
Stock-based compensation expense recognized			$ 100,000

Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Numerator:
Net Income (Loss)	$ (93,053)	$ (98,963)
Denominator:
Weighted-average shares of common stock outstanding	125,062,435	54,407,327
Less: Weighted-average shares of common stock subject to repurchase	(11,790)	(127,063)
Weighted-average shares of common stock outstanding, basic	125,050,645	54,280,264
Weighted-average shares of common stock outstanding, diluted	125,050,645	54,280,264
Net loss per share attributable to common stockholders, basic	$ (0.74)	$ (1.82)
Net loss per share attributable to common stockholders, diluted	$ (0.74)	$ (1.82)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482662/260-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-4

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 105
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 9
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479343/105-10-65-9

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 17
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480336/718-10-65-17

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-6

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 52
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482635/260-10-55-52

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 60
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476176/805-60-65-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 323
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (g)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478666/740-323-65-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482635/260-10-55-15

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (e)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480175/815-40-65-1

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480175/815-40-65-1

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-11

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-11

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-7

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-2

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-60B

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-10

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(25))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(27))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(23))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-7

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 65
-Paragraph 4
-Subparagraph (f)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481538/470-20-65-4

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482662/260-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-4

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 105
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 9
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479343/105-10-65-9

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 17
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480336/718-10-65-17

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-6

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 52
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482635/260-10-55-52

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 60
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476176/805-60-65-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 323
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (g)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478666/740-323-65-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482635/260-10-55-15

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (e)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480175/815-40-65-1

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480175/815-40-65-1

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-11

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-11

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-7

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-2

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-60B

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(25))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(27))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(23))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-7

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 65
-Paragraph 4
-Subparagraph (f)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481538/470-20-65-4

+ Details

- Definition

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

+ References

+ Details

Net Loss Per Share Attributable to Common Stockholders

3 Months Ended

Mar. 31, 2026

Net Loss Per Share Attributable to Common Stockholders

Net Loss Per Share Attributable to Common Stockholders

13.	Net Loss Per Share Attributable to Common Stockholders


		Three Months Ended March 31,
		2026			2025
Numerator:
Net loss		$	(93,053)		$	(98,963)
Denominator:
Weighted-average shares of common stock outstanding			125,062,435			54,407,327
Less: Weighted-average shares of common stock subject to repurchase			(11,790)			(127,063)
Weighted-average shares of common stock outstanding, basic and diluted			125,050,645			54,280,264
Net loss per share attributable to common stockholders, basic and diluted		$	(0.74)		$	(1.82)

The following outstanding potentially dilutive securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented, because including them would have been antidilutive:


		March 31,		March 31,
		2026		2025
Stock options issued and outstanding		22,519,214		13,245,589
RSUs issued and outstanding		3,280,326		—
Common stock issuable under the 2024 ESPP		255,890		158,031
Early exercised stock options and unvested restricted common stock		10,480		102,950
Total		26,065,910		13,506,570