ANAPTYSBIO, INC

Notes to Unaudited Consolidated Financial Statements

1. Description of the Business

AnaptysBio, Inc. (“we,” “us,” “our,” or the “company”) was incorporated in the state of Delaware in November 2005. We are a clinical-stage biotechnology company focused on delivering innovative immunology therapeutics for autoimmune and inflammatory diseases. Our pipeline includes our lead program, rosnilimab, a selective and potent pathogenic T cell depleter, that completed a Phase 2b trial for the treatment of moderate-to-severe rheumatoid arthritis (“RA”) and is in a Phase 2 trial for the treatment of moderate-to-severe ulcerative colitis (“UC”). Our pipeline also includes ANB033, a CD122 antagonist, in a Phase 1b trial for celiac disease (“CeD”) and ANB101, a BDCA2 modulator, in a Phase 1a trial. Anaptys has also discovered and out-licensed in financial collaborations multiple therapeutic antibodies, including a PD-1 antagonist (Jemperli (dostarlimab-gxly) or “Jemperli”) to GSK and an IL-36R antagonist (imsidolimab) to Vanda Pharmaceuticals Inc. (“Vanda”). We currently recognize revenue from milestones and royalties achieved under our immuno-oncology collaboration with GSK and license and transition services revenue from our collaboration with Vanda.

Since our inception, we have devoted our primary effort to research and development activities. Our financial support has been provided primarily from the sale of our common stock and royalty monetizations, as well as through funds received under our collaborative research and development agreements. Going forward, as we continue our expansion, we may seek additional financing and/or strategic investments. However, there can be no assurance that any additional financing or strategic investments will be available to us on acceptable terms, if at all. If events or circumstances occur such that we do not obtain additional funding, we will most likely be required to reduce our plans and/or certain discretionary spending, which could have a material adverse effect on our ability to achieve our intended business objectives. Our management believes our currently available resources will provide sufficient funds to enable us to meet our operating plans for at least the next 12 months from the issuance of our consolidated financial statements. The accompanying consolidated financial statements do not include any adjustments that might be necessary if we are unable to continue as a going concern.

Intention to Separate Company

In September 2025, we announced that our Board of Directors approved plans to explore separating our business intotwo independent, publicly traded companies. One company is expected to hold and continue to manage the Jemperli milestones and royalties from GSK and the milestones and royalties from Vanda with a focus on protecting and returning value of the royalties to its shareholders. The other company is expected to be a clinical-stage biotechnology company focused on the development and potential commercialization of innovative therapeutics for autoimmune and inflammatory diseases, including rosnilimab, ANB033 and ANB101. Upon completion of the separation, which is expected to be completed by year-end 2026, we intend to launch the biotechnology company with adequate capital to fund operations for at leasttwo years. While the separation is anticipated to be a taxable event, we are focused on minimizing overall corporate and shareholder-level taxes across the entire transaction. Completion of the proposed separation is subject to final approval by our Board of Directors and other customary conditions, including the effectiveness of a registration statement with the Securities and Exchange Commission (the “SEC”).

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC. Certain information and note disclosures normally included in annual financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been omitted. The accompanying unaudited consolidated financial statements include all known adjustments necessary for a fair presentation of the results of interim periods as required by U.S. GAAP. These adjustments consist primarily of normal recurring accruals and estimates that impact the carrying value of assets and liabilities. Operating results for the nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025. The financial statements should be read in conjunction with our audited financial statements for the year ended December 31, 2024 included in our Annual Report on Form 10-K.

Basis of Consolidation

The accompanying consolidated financial statements include us and our wholly owned Australian subsidiary, which was deregistered with the Australian Securities & Investments Commission as of September 30, 2025. The deregistration did not have a material impact on our consolidated financial statements. All intercompany accounts and transactions have been eliminated in consolidation. We operate inone reportable segment, and our functional and reporting currency is the U.S. dollar.

Use of Estimates

The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires our management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. We base our estimates and assumptions on historical experience when available and on various factors that we believe to be reasonable under the circumstances. Significant estimates relied upon in preparing these financial statements include estimates related to revenue recognition, accrued research and development expenses, stock-based compensation, and the liability related to the sale of future royalties. We evaluate our estimates and assumptions on an ongoing basis. Our actual results could differ from these estimates under different assumptions or conditions.

Net Income (Loss) Per Common Share

Basic net income (loss) per common share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net income (loss) per share is computed by dividing net income (loss) by the weighted-average number of common equivalent shares outstanding for the period, as well as any dilutive effect from outstanding stock options and awards using the treasury stock method. Computations for basic and diluted net income (loss) per common share are below:

The following table sets forththe weighted-average outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares):

Accounting Pronouncements

We have implemented all new accounting pronouncements that are in effect and may have an impact on our consolidated financial statements. Unless otherwise discussed, we believe the impact of any recently issued and not yet effective pronouncements will not have a material impact on our consolidated financial statements.

Recent Accounting Pronouncements Not Yet Adopted

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures Income Taxes, which improves the transparency of income tax disclosures by requiring consistent categories and greater disaggregation of information in the effective tax rate reconciliation and income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. This guidance will be effective for the annual periods beginning after December 15, 2024. Early adoption is permitted. Upon adoption, the guidance can be applied prospectively or retrospectively. We are currently assessing the impact that this standard will have on our consolidated financial statements.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, which requires disclosure about the types of costs and expenses included in certain expense captions presented on the income statement. The new disclosure requirements are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. We are currently evaluating the provisions of this guidance and assessing the potential impact on our financial statement disclosures.

3. Balance Sheet Accounts and Supplemental Disclosures

Property and Equipment, Net

Property and equipment, net consist of the following:

Accrued Expenses

Accrued expenses consist of the following:

4. Collaborative Research and Development Agreements

GSK Collaboration

In March 2014, we entered into a Collaboration and Exclusive License Agreement (the “GSK Agreement”) with TESARO, Inc. (“Tesaro”), an oncology-focused biopharmaceutical company now a part of GSK (Tesaro and GSK are hereinafter referred to, collectively, as “GSK”). Currently, under the GSK Agreement, GSK is developing Jemperli (dostarlimab) as a monotherapy, and in combination with additional therapies, for various solid tumor indications.

For Jemperli, the remaining development program under the GSK Agreement, we are eligible to receive milestone payments if a European regulatory submission and approval in a second indication is achieved and upon the achievement of specified levels of annual worldwide net sales. On October 23, 2020, Amendment No. 3 to the GSK Agreement (the “GSK Amendment No. 3”) was agreed to by both parties to permit GSK to conduct development and commercialization in combination with any third party molecules of Zejula, an oral, once-daily poly (ADP-ribose) polymerase (PARP) inhibitor (“Zejula”). Under GSK Amendment No. 3, we were granted increased royalties upon sales of Jemperli, equal to 8% of net sales (as defined in the GSK Agreement) below $1.0 billion,12% of net sales between $1.0 billion and $1.5 billion,20% of net sales between $1.5 billion and $2.5 billion and 25% of net sales above $2.5 billion. Unless earlier terminated by either party upon specified circumstances, the GSK Agreement will terminate, with respect to each specific developed product, upon the later of the 12 th anniversary of the first commercial sale of the product or the expiration of the last to expire of any patent.

We assessed these arrangements in accordance with Accounting Standards Codification (“ASC”) 606 and concluded that the contract counterparty, GSK, is a customer. We identified the following material promises under the GSK Agreement: (1) the licenses under certain patent rights and transfer of certain development and regulatory information, (2) research and development (“R&D”) services, and (3) joint steering committee meetings. We considered the research and discovery capabilities of GSK for these specific programs and the fact that the discovery and optimization of these antibodies is proprietary and could not, at the time of contract inception, be provided by other vendors, to conclude that the license does not have stand-alone functionality and is therefore not distinct. Additionally, we determined that the joint steering committee participation would not have been provided without the R&D services and GSK Agreement. Based on these assessments, we identified all services to be interrelated and therefore concluded that the promises should be combined into a single performance obligation at the inception of the arrangement.

As of September 30, 2025, the transaction price for the GSK Agreement and its associated amendments includes the upfront payment, research reimbursement revenue and milestones and royalties earned to date, which are allocated in their entirety to the single performance obligation.

We recognized $26.3 million and $66.6 million in royalty revenue during the three and nine months ended September 30, 2025, respectively, related to GSK’s net sales of Jemperli and Zejula during the period, which we estimate based on either GSK’s prior sales experience or actuals. Of the royalty revenue recognized during the three and nine months ended September 30, 2025, $24.9 million and $63.2 million, respectively, is Jemperli non-cash revenue related to the Jemperli Royalty Monetization Agreement (as amended) and $1.4 million and $3.4 million, respectively, is Zejula non-cash revenue related to the Zejula Royalty Monetization Agreement, each of such agreements as described in Note 5. We recognized $15.0 million and $33.2 million, in royalty revenue during the three and nine months ended September 30, 2024, respectively, related to GSK’s net sales of Jemperli and Zejula during the period based on GSK’s prior sales experience or actuals. Of the royalty revenue recognized during the three and nine months ended September 30, 2024, $13.8 million and $30.1 million, respectively, is

Jemperli non-cash revenue related to the Jemperli Royalty Monetization Agreement (as amended) and $1.2 million and $3.1 million, respectively, is Zejula non-cash revenue related to the Zejula Royalty Monetization Agreement. GSK reports sales information to us on a one quarter lag and differences between actual and estimated royalty revenues will be adjusted in the following quarter.

One sales milestone for $50.0 million was recognized during the three and nine months ended September 30, 2025 when Jemperli annual sales exceeded $750 million, andone sales milestone for $15.0 million was recognized during the three and nine months ended September 30, 2024 when Jemperli annual sales exceeded $250 million. These sales milestones are Jemperli non-cash revenue related to the Jemperli Royalty Monetization Agreement. No other future regulatory milestones have been included in the transaction price, as all future milestone amounts were subject to the revenue constraint. As part of the constraint evaluation, we considered numerous factors including the fact that the receipt of milestones is outside of our control and contingent upon regulatory filing and approval in a second indication, an outcome that is difficult to predict, and GSK’s efforts. Any consideration related to sales-based milestones, including royalties, will be recognized when the related sales occur as they were determined to relate predominantly to the intellectual property license granted to GSK and therefore have also been excluded from the transaction price. We will re-evaluate the variable transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur.

Milestones under the GSK Agreement are as follows:

(1)Biologics License Application (“BLA”)

(2)Marketing Authorization Application (“MAA”)

(3)For Jemperli, the filing and approval of the first MAA for a second indication and first three commercial sales milestones are included as part of the royalty monetization agreement with Sagard (as defined below), see Note 5. Cash is generally received within 30 days of milestone achievement.

(4)For Jemperli, we retained the rights to a $75.0 million sales milestone when Jemperli annual net sales exceed $1.0 billion.

Vanda Collaboration

On January 31, 2025, we entered into an Exclusive License Agreement (the “Vanda License Agreement”) with Vanda pursuant to which we granted to Vanda an exclusive, global license for the development and commercialization of imsidolimab (IL-36R antagonist mAb), which has completed two registration-enabling global Phase 3 trials, GEMINI-1 and GEMINI-2, evaluating the safety and efficacy of imsidolimab in patients with Generalized Pustular Psoriasis (GPP).

Pursuant to the terms of the Vanda License Agreement, we received an upfront payment of $10.0 million for the license and a $5.0 million payment for existing drug supply. We allocated the total transaction price of $15.0 million on a relative standalone selling price in accordance with ASC 606. During the nine months ended September 30, 2025, we recognized $9.6 million of license revenue under ASC 606 and recognizedno license revenue under ASC 606 during the three months ended September 30, 2025. During the three and nine months ended September 30, 2025, we recognized $0.1 million and $0.2 million, respectively, of transition services revenue under ASC 606 and $0.0 million and $5.4 million, respectively, related to existing drug supply transferred to Vanda as other income under ASC 610. We expensed the $2.5 million of related transaction costs within general and administrative expenses, during the nine months ended September 30, 2025, as we elected the practical expedient to expense the transaction costs as incurred as the expected amortization period was less than a year.

We are also eligible to receive a 10% royalty on net sales, as well as the following milestones under the Vanda License Agreement:

Centessa

On November 24, 2023, we entered into an exclusive license agreement (as amended, the “Centessa Agreement”) with Centessa Pharmaceuticals (UK) Limited (“Centessa”), pursuant to which we acquired the exclusive global development and commercialization rights to a blood dendritic cell antigen 2 (BDCA2) modulator antibody portfolio, including lead asset CBS004 (renamed ANB101), CBS008 (renamed ANB102) and the related family of backup antibodies, for the treatment of autoimmune and inflammatory diseases.

In connection with the Centessa Agreement, we paid Centessa an upfront cash payment of $4.0 million and an additional cash payment of $3.0 million as reimbursement to Centessa for manufacturing costs incurred. There were $0.3 million in transaction costs incurred. The total transaction amount of $7.3 million was expensed as in-process research and development and classified as an operating activity in the statement of cash flows. We accounted for the transaction as an asset acquisition as the set of acquired assets did not constitute a business.

Under the terms of the Centessa Agreement, Centessa may be entitled to receive potential future payments of up to $10.0 million upon the achievement of a certain event-based milestone and would be entitled to receive on a product-by-product and country-by-country basis, a royalty of low single digits on annual net sales of any product in the territory in each calendar year. As of September 30, 2025, achievement of the milestone is not probable and, therefore, we have not recognized a liability for the associated $10.0 million contingent consideration.

5. Sale of Future Royalties

Jemperli Royalty Monetization Agreement

In October 2021, we signed a royalty monetization agreement (“Jemperli Royalty Monetization Agreement”) with Sagard Healthcare Royalty Partners, LP (“Sagard”). Under the terms of the Jemperli Royalty Monetization Agreement, we received $250.0 million in exchange for royalties and milestones payable to us under our GSK collaboration on annual global net sales of Jemperli.

In May 2024, we entered into an amendment to the Jemperli Royalty Monetization Agreement, Amendment No. 1 (the “Jemperli Amendment”) under which we sold additional receivables to Sagard in exchange for $50.0 million. The Jemperli Amendment includes all Jemperli sales, including any product containing Jemperli, whether or not such product constitutes a combination product, and the threshold amounts of aggregate Jemperli royalties and milestones to be received by Sagard under the Jemperli Amendment is either $600.0 million if received by the end of March 31, 2031, or $675.0 million if received thereafter. Once either of these thresholds are met, the Jemperli Royalty Monetization Agreement and the Jemperli Amendment will expire, resulting in us regaining all subsequent Jemperli royalties and milestones. As of September 30, 2025, Sagard has received a total of $142.3 million in royalties and milestones, and in addition is expected to be paid a $50.0 million sales milestone in the fourth quarter of 2025.

We retained the rights to a $75.0 million sales milestone when Jemperli annual net sales exceed $1.0 billion.

The proceeds received from Sagard of $250.0 million and $50.0 million were recorded as a nonrecourse liability, net of transaction costs of $0.4 million and $0.1 million, which will be amortized over the estimated life of the arrangement using the effective interest rate method. The aggregate future estimated payments, less the $299.5 million, net of proceeds, will be recognized as non-cash interest expense over the life of the agreement. Royalty and milestone revenue will be recognized as earned on net sales of Jemperli, and these payments to Sagard will be recorded as a reduction of the liability when paid. As such payments are made to Sagard, the balance of the liability will be effectively repaid over the life of the Jemperli Royalty Monetization Agreement.

We estimate the effective interest rate used to record non-cash interest expense under the Jemperli Royalty Monetization Agreement based on the estimate of future royalty payments to be received by Sagard. As of September 30, 2025, the estimated effective rate under the agreement was 30.5%. Over the life of the arrangement, the actual effective interest rate will be affected by the amount and the timing of the royalty payments received by Sagard and changes in our forecasted royalties. At each reporting date, we will reassess our estimate of total future royalty payments to be received and if such payments are materially different than our prior estimates, we will prospectively adjust the imputed interest rate and the related amortization of the royalty obligation.

We recognized Jemperli non-cash royalty revenue of approximately $24.9 million and $63.2 million during the three and nine months ended September 30, 2025, respectively and approximately $13.8 million and $30.1 million during the three and nine months ended September 30, 2024, respectively.

One sales milestone for $50.0 million was recognized during the three and nine months ended September 30, 2025 when Jemperli annual sales exceeded $750 million, andone sales milestone for $15.0 million was recognized during the three and nine months ended September 30, 2024 when Jemperli annual sales exceeded $250 million. These sales milestones are Jemperli non-cash revenue related to the Jemperli Royalty Monetization Agreement.

We recognized non-cash interest expense of approximately $22.3 million and $59.4 million during the three and nine months ended September 30, 2025, respectively, and $15.2 million and $32.0 million during the three and nine months ended September 30, 2024. The interest and amortization of issuance costs are reflected as non-cash interest expense for the sale of future royalties in the Consolidated Statements of Operations.

The following table shows the activity within the liability account for the nine months ended September 30, 2025:

(1)Of the non-cash interest expense recognized, $1.7 million was negative amortization for the nine months ended September 30, 2025.

Zejula Royalty Monetization Agreement

In October 2020, in connection with GSK Amendment No. 3, GSK agreed, under the terms of a settlement agreement (the “GSK Settlement Agreement”), to pay us a royalty of 0.5% on all GSK net sales of Zejula starting January 1, 2021.

In September 2022, we signed a purchase and sale agreement (the “Zejula Royalty Monetization Agreement”) with a wholly owned subsidiary of DRI to monetize all of our future royalties on global net sales of Zejula under the GSK Settlement Agreement. Under the terms of the Zejula Royalty Monetization Agreement, we received $35.0 million in exchange for all royalties payable by GSK to us under the GSK Settlement Agreement on global net sales of Zejula starting in July 2022.

The proceeds received from DRI of $35.0 million were recorded as a nonrecourse liability, net of transaction costs of $0.2 million, which will be amortized over the estimated life of the arrangement using the effective interest rate method. Royalty revenue will be recognized as earned on net sales of Zejula, and these royalty payments to DRI will be recorded as a reduction of the liability when paid. The aggregate future estimated payments, less the $34.8 million, of net proceeds, will be recorded as non-cash interest expense over the life of the agreement. As such payments are made to DRI, the balance of the liability will be effectively repaid over the life of the Zejula Royalty Monetization Agreement.

We recognized Zejula non-cash royalty revenue of approximately $1.4 million and $3.4 million during the three and nine months ended September 30, 2025, respectively, and $1.2 million and $3.1 million during the three and nine months ended September 30, 2024, respectively.

We recognized non-cash interest expense of approximately $0.2 million and $0.7 million during the three and nine months ended September 30, 2025, respectively, and $0.2 million and $0.7 million during the three and nine months ended September 30, 2024, respectively. The interest and amortization of issuance costs is reflected as non-cash interest expense for the sale of future royalties in the Consolidated Statements of Operations.

The following table shows the activity within the liability account for the nine months ended September 30, 2025:

(1)Of the non-cash interest expense recognized, none was negative amortization for the nine months ended September 30, 2025.

6. Fair Value Measurements and Available for Sale Investments

Fair Value Measurements

Our financial instruments consist principally of cash, cash equivalents, short-term and long-term investments, receivables, and accounts payable. Certain of our financial assets and liabilities have been recorded at fair value in the consolidated balance sheet in accordance with the accounting standards for fair value measurements.

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. Accounting guidance also establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value:

Level 1 – Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2 – Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities 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 related assets or liabilities; and

Level 3 – Unobservable inputs that are supported by little or no market activities, therefore requiring an entity to develop its own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table summarizes our assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy:

(1)Included in cash and cash equivalents in the accompanying consolidated balance sheets.

(2)Included in short-term or long-term investments in the accompanying consolidated balance sheets depending on the respective maturity date.

The following methods and assumptions were used to estimate the fair value of our financial instruments for which it is practicable to estimate that value:

Marketable Securities. For fair values determined by Level 1 inputs, which utilize quoted prices in active markets for identical assets, the level of judgment required to estimate fair value is relatively low. For fair values determined by Level 2 inputs, which utilize quoted prices in less active markets for similar assets, the level of judgment required to estimate fair value is also considered relatively low.

Fair Value of Other Financial Instruments

The carrying amounts of certain of our financial instruments, including cash and cash equivalents, receivables, accounts payable, and accrued expenses approximate fair value due to their short-term nature.

Available for Sale Investments

We invest our excess cash in agency securities, debt instruments of financial institutions and corporations, commercial obligations, and U.S. Treasury securities, which we classify as available-for-sale investments. These investments are carried at fair value and are included in the tables above. The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in short-term and long-term investments as of September 30, 2025 are as follows:

(1) Of our outstanding agency securities,$2.5 million have maturity dates of less than one year andnone have maturity dates betweenone totwo years as of September 30, 2025.

(2)Of our outstanding commercial and corporate obligations,$13.6 million have maturity dates of less than one year andnone have a maturity date of betweenone totwo years as of September 30, 2025.

(3) Of our outstanding U.S. Treasury securities,$123.0 million have maturity dates of less than one year and$7.7 million have a maturity date of betweenone totwo years as of September 30, 2025.

The aggregate market value, cost basis, and gross unrealized gains and losses of available for sale investments by security type, classified in short-term and long-term investments as of December 31, 2024 are as follows:

(1) Of our outstanding agency securities, $7.6 million have maturity dates of less than one year and $0.0 million have a maturity date of betweenone totwo years as of December 31, 2024.

(2) Of our outstanding commercial and corporate obligations, $10.7 million have maturity dates of less than one year and $0.0 million have a maturity date of betweenone totwo years as of December 31, 2024.

(3) Of our outstanding U.S. Treasury securities, $249.0 million have maturity dates of less than one year and $35.5 million have a maturity date of betweenone totwo years as of December 31, 2024.

The following tables present gross unrealized losses and fair values for those investments that were in an unrealized loss position as of September 30, 2025 and December 31, 2024, aggregated by investment category and the length of time that individual securities have been in a continuous loss position:

As of September 30, 2025 and December 31, 2024, unrealized losses on available-for-sale investments were less than $0.1 million for both periods, withno available-for-sale investments that were in an unrealized loss position for greater than 12 months as of September 30, 2025. We do not intend to sell the investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost basis, accordingly, no allowance for credit losses was recorded.

7. Stockholders’ Equity

Common Stock

Of the 500,000,000 shares of common stock authorized, 27,575,152 shares were issued and outstanding as of September 30, 2025.

Stock Repurchase Program

In March 2025, our Board of Directors authorized a stock repurchase program (the “2025 Repurchase Program”) to repurchase up to $75.0 million of our outstanding common stock.

The following table presents the repurchase activity through September 30, 2025:

The repurchased common stock was subsequently retired after the repurchase and the par value of the shares was charged to common stock. The excess of the repurchase price over the par value was applied against additional paid in capital. As of September 30, 2025, $9.8 million remained available for future shares of common stock to be repurchased under the 2025 Repurchase Program.

Open Market Sales Agreement

In November 2024, we entered into a sales agreement with TD Securities (USA) LLC (“TD Cowen”), through which we may offer and sell shares of our common stock, having an aggregate offering of up to $100.0 million through TD Cowen as our sales agent. Our prior sales agreement with Cowen terminated upon effectiveness of the registration statement on the Form S-3 we filed in connection with our sales agreement with TD Cowen. As of September 30, 2025, we had soldno shares under this agreement.

Underwriting Agreement

In August 2024, we entered into an underwriting agreement with TD Securities (USA) LLC and Leerink Partners LLC as representatives to the several underwriters listed therein (the “Underwriters”), pursuant to which we issued and sold an aggregate of 2,750,498 shares of our common stock to the Underwriters, at an offering price of $36.50 per share. The net proceeds from these sales were approximately $93.9 million, net of underwriting discounts and commissions and offering expenses of $6.5 million, in the aggregate.

8. Equity Incentive Plans

2017 Equity Incentive Plan

In January 2017, our Board of Directors and stockholders approved and adopted the 2017 Equity Incentive Plan (the “2017 Plan”). Under the 2017 Plan, we may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other awards to individuals who are then our employees, officers, directors or consultants. In addition, the number of shares of stock available for issuance under the 2017 Plan were to be automatically increased each January 1, beginning on January 1, 2018, by 4% of the aggregate number of outstanding shares of our common stock as of the immediately preceding December 31 or such lesser number as determined by our Board of Directors. At our annual stockholder meeting on June 12, 2024, the 2017 Plan was amended, eliminating the automatic annual share increase and the number of shares available for issuance was increased by 2,700,000 shares. At our annual stockholder meeting on June 17, 2025, the 2017 Plan was amended and restated to further increase the number of shares available for issuance by 1,650,000 shares. All future share increases will require stockholder approval. As of September 30, 2025,2,501,977 shares were available for future issuance.

Employee Stock Purchase Plan

In January 2017, our Board of Directors and stockholders approved and adopted the 2017 Employee Stock Purchase Plan (“ESPP”). In addition, the number shares of stock available for issuance under the ESPP will be automatically increased each January 1, beginning on January 1, 2018, by 1% of the aggregate number of outstanding shares of our common stock as of the immediately preceding December 31 or such lesser number as determined by our Board of Directors. The Board of Directors determined that due to sufficient shares being available in the ESPP, the number of shares available as of January 1, 2025 would not increase. As of September 30, 2025,241,606 shares have been issued under the ESPP and 1,857,201 shares were available for future issuance under the ESPP. Total cash received from the ESPP was approximately $1.0 million during the nine months ended September 30, 2025.

Stock Options

Stock options granted to employees and non-employees generally vest over afour-year period while stock options granted to directors generally vest over aone-year period. Each stock option award has a maximum term of 10 years from the date of grant, subject to earlier cancellation prior to vesting upon cessation of service to us. A summary of the activity related to stock option awards during the nine months ended September 30, 2025 is as follows:

Total cash received from the exercise of stock options was approximately $1.1 million during the nine months ended September 30, 2025.

Time-Based Restricted Stock Units

Each Restricted Stock Unit (“RSU”) representsone equivalent share of our common stock to be issued after satisfying the applicable continued service-based vesting criteria over a specified period. The fair value of these RSUs is based on the closing price of our common stock on the date of the grant. We measure compensation expense over the expected vesting period on a straight-line basis. The RSUs do not entitle the participants to the rights of holders of common stock, such as voting rights, until the shares are issued.

Performance Stock Units

A Performance Stock Unit (“PSU”) representsone equivalent share of our common stock to be issued after achievement of the performance metrics specified in the grant. The fair value of our PSUs is estimated as of the grant date of July 22, 2024, based upon the expected achievement of the performance metrics specified in the grant and the closing market price of our common stock on the date of grant. The grant date fair value is estimated using a Monte Carlo simulation using the following assumptions:

The compensation expense for the awards is recognized over the requisite service period regardless of whether the market conditions are achieved and will only be adjusted for pre-vesting forfeitures due to the termination of the recipient’s employment with the company prior to the expiration of the requisite service period. The requisite service period over which the compensation expense will be recognized is July 22, 2024 through July 1, 2028.

The following table presents a summary of activity with respect to our PSUs:

Stock-Based Compensation Expense

We recognize stock-based compensation expense for awards issued to employees and non-employees over the requisite service period based on the estimated grant-date fair value of such awards. We record the expense for stock-based compensation awards subject to performance-based milestone vesting over the requisite service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the expected satisfaction of the performance conditions at each reporting date. The estimated fair values of stock option awards granted were determined on the date of grant using the Black-Scholes option valuation model with the following weighted-average assumptions:

We determine the appropriate risk-free interest rate, expected term for employee stock-based awards, contractual term for non-employee stock-based awards, and volatility assumptions. The weighted-average expected option term for employee and non-employee stock-based awards reflects the historical option term. Expected volatility incorporates the historical volatility of our stock price. The risk-free interest rate is based upon U.S. Treasury securities with remaining terms similar to the expected or contractual term of the stock-based payment awards. The assumed dividend yield is based on our expectation of not paying dividends in the foreseeable future.

Total non-cash stock-based compensation expense for all stock awards that was recognized in the consolidated statements of operations and comprehensive loss is as follows:

At September 30, 2025, there was $47.7 million of unrecognized compensation cost related to unvested stock option awards, which is expected to be recognized over a remaining weighted-average vesting period of 2.58 years, $22.4 million of unrecognized cost related to unvested RSU awards, which is expected to be recognized over a period of 2.51 years, $8.6 million of unrecognized cost related to unvested PSU awards, which is expected to be recognized over a period of 2.78 years, and $0.1 million of unrecognized compensation cost related to the ESPP, which is expected to be recognized over a remaining weighted-average vesting period of 0.13 years.

9. Commitments and Contingencies

Operating Leases

On May 4, 2020, we entered into a lease agreement with Wateridge Property Owner, LP, with respect to facilities in the building at 10770 Wateridge Circle, San Diego, California 92121 (the “Lease Agreement”). Under the Lease Agreement, we agreed to lease approximately 45,000 square feet of space for a term of 124 months, beginning on April 5, 2021. The terms of the Lease Agreement provide us with an option to extend the term of the lease for an additional five years, as well as a one-time option to terminate the lease after seven years, on April 30, 2028 with the payment of a termination fee of $3.8 million plus 15-months of operating expenses and real property taxes. The exercise of the lease option is at our sole discretion, which we currently do not anticipate exercising and as such was not recognized as part of the right-of-use asset (the “ROU asset”) and lease liability. The monthly base rent was initially $4.20 per rentable square foot and is increased by 3% annually. Under the Lease Agreement, we are also responsible for our pro rata share of real estate taxes, building insurance, maintenance, direct expenses, and utilities. Upon lease commencement, on April 5, 2021, we recognized an ROU asset of $20.6 million, with a corresponding lease liability of $20.7 million on the consolidated balance sheets. The ROU asset includes adjustments for prepayments, initial direct costs, and lease incentives. As of September 30, 2025, we have recorded $0.3 million as a security deposit in accordance with the terms of the Lease Agreement.

Our lease payments are fixed, and we recognize lease expense for leases on a straight-line basis over the lease term. Operating lease ROU assets and lease liabilities are recorded based on the present value of the future minimum lease payments over the lease term at commencement date. As our lease does not provide an implicit rate, we used our incremental borrowing rate based on the information available at the lease commencement date in determining the present value of future payments. The weighted-average discount rate used was 4.0% and the weighted-average remaining lease term is approximately 5.9 years.

The following non-cancellable office lease costs are included in our consolidated statements of cash flow (in thousands):

At September 30, 2025, the future minimum annual obligations for our operating lease liabilities are as follows (in thousands):

10. Segment Reporting

We operate asone reportable segment focused on research and development activities to deliver immunology therapeutics for autoimmune and inflammatory diseases. Segment profit or loss is measured as the net income (loss) reported on our Consolidated Statements of Operations and Comprehensive Income (Loss) and net income (loss) is used to monitor results. Our segment revenue consists of milestone payments, royalty payments, upfront license fees and transition services provided under our collaboration agreements, see Note 4. The measure of segment assets is reported on our Consolidated Balance Sheets as total assets.

The CODM is our Chief Executive Officer. The CODM manages the business activities on a consolidated basis in making decisions regarding resource allocation and performance assessment.

The following table is a summary of segment revenue, income (loss) and our significant expenses (in thousands):

(1) External R&D consists of costs associated with our research and development activities, including drug discovery efforts, preclinical and clinical development of our programs, manufacturing, and allocated facility-related costs.

(2) Internal R&D and G&A consist of salaries and wages, stock-based compensation, recruiting and other employee benefits.

(3) External G&A consists of general and administrative expenses including transaction costs, legal services, insurance, professional fees for auditing, tax, and market research, and allocated facility-related costs not otherwise included in research and development expenses.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q (“Quarterly Report”) contains forward-looking statements within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and section 27A of the Securities Act of 1933, as amended (the “Securities Act”). The words “believe,” “may,” “will,” “potentially,” “estimate,” “continue,” “anticipate,” “intend,” “could,” “would,” “project,” “plan,” and “expect,” and similar expressions that convey uncertainty of future events or outcomes, are intended to identify forward-looking statements.

The forward-looking statements in this Quarterly Report include, among other things, statements about:

•the success, cost, and timing of our product candidate development activities and ongoing and planned clinical trials;

•our plans and ability to develop and commercialize antibodies;

•the likelihood that the clinical data generated in any study we performed, are performing, or plan to perform in a non-U.S. jurisdiction will be subsequently accepted by the U.S. Food and Drug Administration (“FDA”) and/or by foreign regulatory authorities outside of the jurisdiction where the study was being performed;

•the potential benefits and advantages of our product candidates and approaches versus those of our competitors;

•the success of competing therapies that are or may become available;

•the timing of and the ability to obtain and maintain regulatory approvals for our product candidates, partnered product candidates and/or product candidates for which we may receive royalties;

•the rate and degree of market acceptance and clinical utility of any approved product candidates;

•the size and growth potential of the markets for any approved product candidates, and our ability to serve those markets;

•regulatory developments in the United States (“U.S.”) and foreign countries;

•the impact of political, economic or public health events on our business and the U.S. and global economies;

•our ability to attract and retain key scientific or management personnel;

•general macroeconomic factors, including volatility in equity markets, and fluctuations in interest rates, foreign exchange rates and political and regulatory developments or changes in trade policy, including tariffs;

•our ability to obtain funding for our operations on favorable terms or at all, including funding necessary to complete further development and commercialization of our product candidates;

•the timing and ability of our collaborators to develop and commercialize our partnered product candidates;

•the proposed separation of the Company’s operations into two independent, publicly traded companies, including the completion and timing of the separation, the business and operations of each company and any benefits or costs of the separation;

•expectations regarding the structure, infrastructure, timing and taxation of the proposed separation of companies;

•our use of the net proceeds from our public offerings and other financing transactions; and

•our estimates regarding expenses, future revenue, capital requirements, and needs for additional financing.

These forward-looking statements are subject to a number of risks, uncertainties, and assumptions, including those described in Part II, Item 1A, “Risk Factors,” and elsewhere in this Quarterly Report. Moreover, we operate in a competitive and rapidly changing environment, and new risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties, and assumptions, the forward-looking events and circumstances discussed in this Quarterly Report may not occur, and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements.

You should not rely upon forward-looking statements as predictions of future events. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance, or events and circumstances reflected in the forward-looking statements will be achieved or occur. We undertake no obligation to update publicly any forward-looking statements to conform these statements to actual results or to changes in our expectations, except as required by law.

You should read this Quarterly Report with the understanding that our actual future results, levels of activity, performance, and events and circumstances may be materially different from what we expect.

Unless the context indicates otherwise, as used in this Quarterly Report, the terms “AnaptysBio,” “Anaptys,” “company,” “we,” “us” and “our” refer to AnaptysBio, Inc., a Delaware corporation, and its subsidiaries taken as a whole, unless otherwise noted. AnaptysBio is our common law trademark. This Quarterly Report contains additional trade names, trademarks, and service marks of other companies, which are the property of their respective owners. We do not intend our use or display of other companies’ trade names, trademarks, or service marks to imply a relationship with, or endorsement or sponsorship of us by, these other companies.