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 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 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 350 Intangibles - 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 been no 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.