ALUMIS INC.

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 June 30, 2026, the Company hadtwo 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.

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 U.S. Securities and Exchange Commission (“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 of 1933, as amended (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 June 30, 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 and six months ended June 30, 2026 and 2025, the Company incurred net income (loss) of $(142.2) million, $59.3 million, $(235.3) million and $(39.6) million, respectively. Cash used in operating activities was $168.6 million and $186.7 million for the six months ended June 30, 2026 and 2025, respectively. As of June 30, 2026, the Company had an accumulated deficit of $1,137.2 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 $502.3 million as of June 30, 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.

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 six months ended June 30, 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 June 30, 2026 and its results of operations for the three and six months ended June 30, 2026 and 2025 and its cash flows for the six months ended June 30, 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 and six months ended June 30, 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 asone 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 15 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 revenue recognized in its condensed consolidated statements of operations and comprehensive income (loss) for the three and six months ended June 30, 2026 and 2025, was 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 economic uncertainty, general market volatility and geopolitical tensions, including the ongoing Russia-Ukraine military conflict and the ongoing military conflict involving the U.S., Israel and Iran. Escalation or expansion of these conflicts, as well as related sanctions, export controls, trade restrictions and the disruption of global energy markets, fuel prices, transportation networks, and supply chains, may disrupt or otherwise negatively impact the Company’s supply chain and increase its costs. These geopolitical developments, together with evolving global economic conditions, trade policies and broader macroeconomic conditions may negatively impact the Company’s business, financial position and results of operations.

Intangible Assets

Intangible assets related to acquired IPR&D are considered to be indefinite-lived until abandonment or completion of the associated research and development efforts, which generally occurs when regulatory approval is obtained. Indefinite-lived intangible assets are not amortized and, instead, are tested for impairment annually in the fourth quarter, or more frequently if events or changes in circumstances indicate that it is more likely than not that the assets are impaired as required by ASC 350Intangibles - Goodwill and Other (“ASC 350”). Such events and circumstances may include

significant changes in the Company’s business climate, economic and industry trends, legal or regulatory factors, clinical trial results, significant competition or changes in development strategy.

The Company may first perform a qualitative assessment to determine whether it is necessary to perform a quantitative impairment test. Alternatively, the Company may elect to proceed directly to a quantitative impairment test. The quantitative impairment test compares the fair value of the indefinite-lived intangible asset with its carrying amount. If the carrying amount exceeds fair value, an impairment loss is recognized for the excess and the carrying amount of the asset is reduced accordingly. After an impairment loss is recognized, the adjusted carrying amount of the intangible asset becomes its new accounting basis.

In determining the initial fair value of an intangible asset, or when quantitative analysis is required to determine any impairment, the Company usually uses an income approach that discounts expected future cash flows to present value using a discount rate that is based on the estimated weighted-average cost of capital for comparable companies and represents the rate that market participants would use to value the intangible asset. These cash flow models require the use of Level 3 fair value measurements and inputs, including estimated revenues, costs and probabilities of achieving technical and regulatory milestones, among other factors. The Company recognized an intangible assets impairment loss for the three and six months ended June 30, 2026. See Note 6 for additional information.

Intangible assets with finite useful lives, which include completed IPR&D projects, are amortized over their estimated useful lives, primarily on a straight-line basis, and are also periodically reviewed for changes in facts or circumstances that may result in an impairment or in a reduction to the estimated useful life of the asset.

Development costs incurred after an acquisition are expensed as they are incurred.

Income Taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes.

The Company assesses the likelihood of deferred tax assets being realized. It provides a valuation allowance when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible.

The Company recognizes the tax benefit from an uncertain tax position if it is more likely than not that the tax position will be sustained upon examination by the tax authorities, based on the merits of the position. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have beenno interest or penalties incurred in relation to unrecognized tax benefits.

The Company recognized a benefit from income taxes of $1.8 million for the three and six months ended June 30, 2026, which was primarily related to the reduction of deferred tax liabilities, partially offset by an increase in valuation allowance resulting from the measurement of its acquired IPR&D intangible asset at fair value in connection with an impairment assessment. The Company recognized a benefit from income taxes of $8.6 million for the three and six months ended June 30, 2025, which was primarily related to the realization of deferred tax assets and valuation allowance release resulting from the ACELYRIN Merger.

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.

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. Assumed performance RSUs were deemed to have 100% satisfied their performance conditions and vest intwo 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):

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):

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. See Note 6 for additional information.

The Company acquired a prepaid credit voucher for clinical manufacturing issued by one of ACELYRIN’s contract manufacturers that is applied towards payments of clinical product manufacturing invoices issued by the vendor. The 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 acquiredtwo operating leases and a sublease. See Note 10 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 was primarily related 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 income (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 had additional severance-related obligations under the Merger Agreement that were separate from the assets and liabilities acquired in the Merger. In accordance with the ACELYRIN severance plan, ACELYRIN employees who were terminated without cause within 12 months of the Closing Date were entitled to severance benefits, including cash severance, accelerated vesting of outstanding equity awards and an extension of the post-termination exercise period of outstanding stock options of generally up to 12 months.

The Company estimated total cash severance obligation, including related payroll taxes, of$11.9 million. The severance obligation was recognized over the remaining requisite service periods of the affected employees and was substantially paid by December 31, 2025. The Company recognized$5.2 million as general and administrative expenses and$3.7 million as research and development expenses related to severance expenses for the three and six months ended June 30, 2025. The Company recognized$6.5 million as general and administrative expenses and$5.4 million as research and development expenses related to severance expenses for the year ended December 31, 2025. No severance expense was recognized for the three and six months ended June 30, 2026.

The Company estimated stock-based compensation expense of$13.1 million related to the accelerated vesting of equity awards and the post-termination exercise period extensions granted to affected employees, which was fully recognized during the year ended December 31, 2025. The Company recognized stock-based compensation expense of$10.8 million related to these arrangements for the three and six months ended June 30, 2025, consisting of$7.8 million in general and administrative expenses and$3.0 million in research and development expenses. The Company recognized stock-based compensation expense of$13.1 million for the year ended December 31, 2025, consisting of$9.0 million in general and administrative expenses and$4.1 million in research and development expenses. No stock-based compensation expense related to these arrangements was recognized for the three and six months ended June 30, 2026.

In addition, the Company recognized ACELYRIN Merger transaction costs of$7.1 million and$14.8 million in general and administrative expenses for the three and six months ended June 30, 2025, respectively. No ACELYRIN Merger transaction costs were recognized during the three and six months ended June 30, 2026.

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.

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.

Recurring Fair Value Measurements

The following tables present the Company’s fair value hierarchy for financial assets measured at fair value on a recurring basis as of June 30, 2026 and December 31, 2025 (in thousands):

The Company did not hold Level 3 financial instruments measured on a recurring basis and there wereno transfers between Level 1 and Level 2 categories during the six months ended June 30, 2026 and 2025.

Nonrecurring Fair Value Measurements

During the three months ended June 30, 2026, the Company measured its acquired IPR&D intangible asset at fair value on a nonrecurring basis in connection with an impairment assessment. The fair value measurement was classified within Level 3 of the fair value hierarchy. Based on the assessment, the Company recorded an impairment loss of $41.8 million during the three and six months ended June 30, 2026. See Note 6 for additional information.

Marketable securities, which are classified as available-for-sale, consisted of the following as of June 30, 2026 and December 31, 2025 (in thousands):

Marketable securities classified as current as of June 30, 2026 and December 31, 2025 had contractual maturities of one year or less from the purchase date.

As of June 30, 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 thereforeno allowance for expected credit losses was recorded for the three and six months ended June 30, 2026 and 2025.

**6.**Intangible Assets

Intangible assets consist of the acquired IPR&D intangible asset related to the lonigutamab product candidate acquired in the ACELYRIN Merger at its estimated fair value of $51.0 million as of the Closing Date. See Note 3 for additional information. The 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.

In May 2026, the Company completed its strategic review of the lonigutamab program and decided to pursue strategic alternatives for the program. This decision represented a triggering event under ASC 350 and required the Company to perform an interim impairment assessment of the acquired IPR&D intangible asset. Based on the results of the impairment assessment, the Company recorded an intangible assets impairment loss of $41.8 million, which was recognized as a separate line item in operating expenses, in its unaudited condensed consolidated statement of operations and

comprehensive income (loss) for the three and six months ended June 30, 2026. The impairment loss reduced the carrying value of the acquired IPR&D intangible asset to its estimated fair value of $9.1 million as of June 30, 2026.

The fair value of the acquired IPR&D intangible asset was determined using a weighted scenario-based, risk-adjusted discounted cash flows method, which estimates the present value of projected future cash flows attributable to the asset under multiple potential outcomes and applies probability weightings ranging from 10% to 70%. The valuation incorporated significant unobservable inputs and assumptions including the probability and timing of potential strategic transactions, such as out-licensing arrangements, estimated future cash flows, projected revenues, the probability of technical and regulatory success and a discount rate of 24%.

**7.**Balance Sheet Components

Restricted Cash

Restricted cash consists of cash pledged as collateral for stand-by letters of credit of $1.4 million and $1.3 million as of June 30, 2026 and December 31, 2025, respectively. Substantially all of the restricted cash relates to lease commitments and will remain restricted until the termination or modification of the underlying lease agreements. Restricted cash was classified as non-current in the condensed consolidated balance sheets as of June 30, 2026 and December 31, 2025.

Other Prepaid Expenses and Current Assets

Other prepaid expenses and current assets consisted of the following as of June 30, 2026 and December 31, 2025 (in thousands):

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 June 30, 2026, the prepaid credit voucher for clinical manufacturing included $13 thousand classified in other prepaid expenses and current assets and $0.9 million included in other assets, non-current.

Property and Equipment, Net

Property and equipment, net consisted of the followingas of June 30, 2026 and December 31, 2025(in thousands):

Depreciation and amortization expense was $0.8 million and $0.9 million for the three months ended June 30, 2026 and 2025, respectively and $1.7 million for each of the six months ended June 30, 2026 and 2025.

Other Accrued Expenses and Current Liabilities

Other accrued expenses and current liabilities consisted of the following as of June 30, 2026 and December 31, 2025 (in thousands):

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 license revenue ofzero for the three and six months ended June 30, 2026, andzero and $17.4 million for the three and six months ended June 30, 2025, respectively, related to the License Obligation. The Company recognized collaboration revenue of $1.7 million and $3.4 million for the three and six months ended June 30, 2026, respectively, and $2.7 million for the three and six months ended June 30, 2025, related to the Development Services Obligation and Manufacturing Services Obligation. As of June 30, 2026, collaboration revenue receivable waszero, deferred revenue, current was $6.7 million and deferred revenue, non-current waszero. 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 $1.7 million andzero for the three months ended June 30, 2026 and 2025, respectively and was $3.4 million andzero for the six months ended June 30, 2026 and 2025, respectively. The aggregate estimated amount of transaction price that was unsatisfied as of June 30, 2026 was $14.2 million, of which, $10.9 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 June 30, 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. The Company disputes Climb Bio’s interpretation and, in January 2026, issued a notice of material breach to Climb Bio for failing to timely pay a $3.0 million development milestone. The Company 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.

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 additionalone-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 $0.4 million and $0.3 million as research and development expenses under the services agreement for the three months ended June 30, 2026 and 2025, respectively. The Company recognized $0.5 million as research and development expenses under the services agreement for each of the six months ended June 30, 2026 and 2025. There wereno accrued expenses under the services agreement as of June 30, 2026 and December 31, 2025.

**10.**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 toextend the lease for an additionaltwo 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, undiscounted 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 additionaltwo years ending in December 2028. As of the lease modification date, undiscounted future lease payments totaled $2.9 million, and the lease liability was calculated as $2.5 million, which is equal to the present value of future lease payments, discounted at an incremental borrowing rate of 9.3%. The amended agreement has an option to extend the lease for an additionaltwo 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 thousand, 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 and six months ended June 30, 2026. In April 2026, the Company delivered a notice of termination to the sublessee, and the sublease was 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$0.2 million, 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 and six months ended June 30, 2026.

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

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:

Future minimum lease payments under non-cancelable leases as of June 30, 2026, were as detailed below (in thousands):

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. 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. No additional milestones were achieved or were probable of being achieved as of June 30, 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 June 30, 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 $0.6 million as of June 30, 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 income (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 (the “Court”). 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 June 30, 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 June 30, 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.

As of June 30, 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 withpar values of $0.0001 per share. As of June 30, 2026, there wereno shares of preferred stock issued or outstanding,124,445,537 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 toone 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 June 30, 2026 and December 31, 2025:

Common Stock Issued to Executives

In February 2021, the Company issued 100,532 shares of restricted common stock totwo executives at a purchase price of $0.94 per share. The shares vested over afour-year period with aone-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 restricted common stock fully vested as of March 31, 2025. The Company recognized less than $0.1 million of stock-based compensation expense for the three and six months ended June 30, 2025.

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 applicablesix-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 offive 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 six months ended June 30, 2026 and includes early exercised shares as part of stock options exercised:

Total exercisable shares of 9,104,174 as of June 30, 2026 included 1,422,383 unvested shares that were early exercisable under the 2021 Plan. The total fair value of stock options vested during the six months ended June 30, 2026 and 2025 was $13.1 million and $15.6 million, respectively.

The following table summarizes the Company’s stock option activity under the 2024 POP for the six months ended June 30, 2026:

Valuation of Stock Options Granted

The weighted-average grant date fair value of stock options granted for the six months ended June 30, 2026 and 2025 was $20.60 and $4.02 per stock option, respectively.

The fair value of stock options granted for the six months ended June 30, 2026 and 2025 was estimated using the Black-Scholes option pricing model with the following assumptions:

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 ofzero 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 June 30, 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 six months ended June 30, 2026:

2024 Employee Stock Purchase Plan

In June 2024, the Company’s board of directors adopted, and its stockholders approved, the 2024 Employee Stock Purchase Plan (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 forten 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 six months ended June 30, 2026 and 2025,253,150 and 184,633 shares of common stock were purchased under the 2024 ESPP, respectively.

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 six months ended June 30, 2026:

Restricted Stock Units

The following table summarizes the Company’s unvested RSUs activity for the six months ended June 30, 2026:

Stock-Based Compensation Expense

The following table summarizes the stock-based compensation expense recognized in the Company’s unaudited condensed consolidated statements of operations and comprehensive income (loss) for the three and six months ended June 30, 2026 and 2025 (in thousands):

The following table summarizes stock-based compensation expense recognized in the Company’s unaudited condensed consolidated statements of operations and comprehensive income (loss) by award type for the three and six months ended June 30, 2026 and 2025 (in thousands):

Stock-based compensation expense related to non-employee awards was $0.4 million and $0.1 million for the three months ended June 30, 2026 and 2025, respectively, and was $0.7 million and $0.3 million for the six months ended June 30, 2026 and 2025, respectively. Stock-based compensation expense related to the 2024 POP was $0.9 million and $2.1 million for the three months ended June 30, 2026 and 2025, respectively, and $2.2 million and $4.3 million for the six months ended June 30, 2026 and 2025, respectively. Stock-based compensation expense for the three and six months ended June 30, 2025 included $10.8 million in severance costs related to the ACELYRIN Merger. See Note 3 for additional information.

As of June 30, 2026, unrecognized stock-based compensation expense for all stock awards was $152.3 million, which the Company expects to recognize over a weighted-average period of 2.9 years.

**13.**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 $0.4 million and $1.4 million to the 401(k) plan during the three and six months ended June 30, 2026, respectively.

The following table presents the computation of the basic and diluted net income (loss) per share attributable to common stockholders for the three and six months ended June 30, 2026 and 2025 (in thousands, except share and per share amounts):

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

For purposes of evaluating performance and allocating resources, the Company’s CODM, its Chief Executive Officer, regularly reviews consolidated net income (loss) as reported in the Company’s consolidated statements of operations and comprehensive income (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 income (loss) presented in the Company’s condensed consolidated statements of operations and comprehensive income (loss), see below for disaggregated amounts that comprise research and development expenses for the three and six months ended June 30, 2026 and 2025 (in thousands):