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. Prior to the separation described below, we were a clinical-stage biotechnology company focused on delivering innovative immunology therapeutics for autoimmune and inflammatory diseases. Our clinical-stage pipeline included rosnilimab, a selective pathogenic T cell depleter, for which we completed a Phase 2b trial for the treatment of moderate-to-severe rheumatoid arthritis (“RA”), ANB033, a CD122 antagonist, in a Phase 1b trial for celiac disease (“CeD”) and eosinophilic esophagitis (“EoE”), and ANB101, a BDCA2 modulator, in a Phase 1a trial. We 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 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.

In September 2025, we announced that our board of directors (“Board of Directors”) approved plans to explore separating our business intotwo independent, publicly traded companies. We would hold and continue to manage the financial collaboration for Jemperli with GSK and for imsidolimab with Vanda, with a focus on protecting and returning value of the royalties to its stockholders. The spun-out company would 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. This separation was completed on April 20, 2026.

In connection with the separation, we entered into a separation and distribution agreement (the “Separation and Distribution Agreement”) with First Tracks Biotherapeutics, Inc. (“First Tracks Biotherapeutics”). The Separation and Distribution Agreement identifies the assets transferred to (including the contracts assigned) or retained by, and the liabilities assumed or retained by, each of us and First Tracks Biotherapeutics. As the separation occurred after March 31, 2026, the results of First Tracks Biotherapeutics are included within continuing operations in our consolidated financial statements.

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 U.S. Securities and Exchange Commission (“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 three months ended March 31, 2026 are not necessarily indicative of the results that may be expected for the year ending December 31, 2026. The financial statements should be read in conjunction with our audited financial statements for the year ended December 31, 2025 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 June 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 intwo reportable segments, 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 Loss Per Common Share

Basic net loss per common share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net 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. For each period presented, there is no difference in the number of shares used to calculate basic and diluted net loss per share, as we are in a loss position for both periods and all shares are anti-dilutive.

The following table sets forth the 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 pronouncements will not have a material impact on our consolidated financial statements.

Recent Accounting Pronouncements Not Yet Adopted

In November 2024, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“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.

In December 2025, the FASB issued ASU No. 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements, which clarifies the guidance in Topic 270 to improve the consistency of interim financial reporting. The ASU provides a comprehensive list of required interim disclosures and introduces a disclosure principle requiring entities to disclose events since the end of the last annual period that have a material impact on the entity. ASU 2025-11 is effective for fiscal years beginning after December 15, 2027, including interim periods within those fiscal years, with early adoption permitted. We are currently evaluating the impact of adoption 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. 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 March 31, 2026, 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$25.5 million in royalty revenue during the three months ended March 31, 2026 related to GSK’s net sales of Jemperliand 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 months ended March 31, 2026, $24.6 million is Jemperlinon-cash revenue related to the Jemperli Royalty Monetization Agreement (as amended), and $0.9 million is Zejula non-cash revenue related to the Zejula Royalty Monetization Agreement, each of such agreements as described in Note 5. We recognized $18.1 million in royalty revenue during thethree months ended March 31, 2025, related to GSK’s net sales of Jemperliand Zejula during the period based on GSK’s prior sales experience or actuals. Of the royalty revenue recognized during the three months ended March 31, 2025, $17.2 million is Jemperlinon-cash revenue related to the Jemperli Royalty Monetization Agreement (as amended) and $0.9 million 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.

No clinical or sales milestones were recognized during the three months ended March 31, 2026 and 2025. No other future clinical or 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. 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). For more information, 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 exceeded $1.0 billion. We received the cash milestone payment in December 2025.

We are currently party to litigation with GSK with respect to the GSK Agreement. See Item 1. “Legal Proceedings” for additional information.

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 thethree months ended March 31, 2026, we recognizedno license revenue and less than $0.1 million of transition services revenue. During thethree months ended March 31, 2025, we recognized $9.6 million of license revenue and $0.1 million of transition services revenue, under ASC 606, and recognized $1.9 million related to existing drug supply transferred to Vanda, under ASC 610. We expensed the $2.5 millionof related transaction costs within general and administrative expenses, during the three months ended March 31, 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:

The Separation and Distribution Agreement provides that any and all rights to receive milestone payments under the Vanda License Agreement will be allocated to First Tracks Biotherapeutics.

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) and the related family of 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 March 31, 2026, 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 March 31, 2026, Sagard has received a total of $249.3 million in royalties and milestones.

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 March 31, 2026, the estimated effective rate under the agreement was 34.9%. 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.

No sales milestones were recognized during thethree months ended March 31, 2026 and 2025.

We recognized Jemperlinon-cash royalty revenue of approximately$24.6 millionand $17.2 million during thethree months ended March 31, 2026 and 2025, respectively, and non-cash interest expense of approximately $20.9 million and $17.8 million during thethree months ended March 31, 2026 and 2025, respectively. 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 thethree months ended March 31, 2026:

(1)

Of the non-cash interest expense recognized, none was negative amortization for thethree months ended March 31, 2026.

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 approxim ately $0.9 million during each of the three months ended March 31, 2026 and 2025 and recognized negative non-cash interest expense of less than $0.1 million duringthe three months ended March 31, 2026 and non-cash interest expense of $0.2 million for thethree months ended March 31, 2025. 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 thethree months ended March 31, 2026:

(1)

Of the non-cash interest expense recognized, none was negative amortization for thethree months ended March 31, 2026.

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 in the accompanying consolidated balance sheets.

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 March 31, 2026 are as follows:

(1)

Of our outstanding commercial and corporate obligations, $5.0 million have maturity dates of less than one year and $0.0 million have a maturity date of betweenone totwo years as of March 31, 2026.

(2)

Of our outstanding U.S. Treasury securities, $33.0 million have maturity dates of less than one year and $0.0 million have a maturity date of betweenone totwo years as of March 31, 2026.

The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents, short-term, and long-term investments as of December 31, 2025 are as follows:

(1)

Of our outstanding commercial and corporate obligations, $10.2 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, 2025.

(2)

Of our outstanding U.S. Treasury securities, $63.3 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, 2025.

There wereno available-for-sale investments in an unrealized loss position as of March 31, 2026 or December 31, 2025. Accordingly, no allowance for credit losses was recorded.

7. Stockholders’ Equity

Common Stock

Of the 500,000,000 shares of common stock authorized,29,030,784 shares were issued and outstanding as of March 31, 2026.

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. In November 2025, our Board of Directors authorized an amendment to the 2025 Repurchase Program, under which an additional $100.0 million of our outstanding common stock may be repurchased. During the three months ended March 31, 2026, there wereno repurchases made and the 2025 Repurchase Program expired on March 31, 2026.

In March 2026, our Board of Directors authorized a stock repurchase program (the “2026 Repurchase Program”) to repurchase up to $100.0 million of our outstanding common stock. As of March 31, 2026, $100.0 million remained available for future shares of common stock to be repurchased under the 2026 Repurchase Program.

Open Market Sales Agreement

In November 2024, we entered into an open market sales agreement (the “Open Market Sales Agreement”) with TD Securities (USA) LLC (“TD Cowen”), under which we may offer and sell shares of our common stock up to an aggregate offering of $100.0 million through TD Cowen as our sales agent. Our prior sales agreement with TD Cowen terminated upon effectiveness of the registration statement on the Form S-3 we filed in connection with the Open Market Sales Agreement. The Open Market Sales Agreement was terminated in March 2026 withno shares sold.

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 March 31, 2026,1,813,795 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 of 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 and January 1, 2026 would not increase. As of March 31, 2026,294,081 shares have been issued under the ESPP and 1,804,726 shares were available for future issuance under the ESPP. Total cash received from the ESPP was approximately $0.8 million during the three months ended March 31, 2026.

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 thethree months ended March 31, 2026 is as follows:

Total cash received from the exercise of stock options was approximately $13.2 million during the three months ended March 31, 2026.

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

Market-Based Awards

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.

Performance-Based PSUs

The performance-based stock units granted in 2026 vested in March 2026 based upon (i) continued service through the vesting date and (ii) the achievement of specific performance targets, as approved by the Board of Directors. There wasno unrecognized compensation expense as of March 31, 2026.

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 March 31, 2026, there was $48.8 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 2.48 years,$34.3 millionof unrecognized cost related to unvested RSU awards, which is expected to be recognized over a period of 2.58 years and $6.5 millionof unrecognized cost related to unvested PSU awards, which is expected to be recognized over a period of 2.00 years.

On March 26, 2026, our then Chief Financial Officer and Chief Legal Officer entered into transition and separation agreements, conditioned upon and effective on the Spin-Off (as defined below). In connection with their transition and separation agreements, we modified certain equity awards and recognized approximately $2.0 million in non-cash stock-based compensation expense during the three months ended March 31, 2026.

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 extension 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 March 31, 2026, 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 5.4 years.

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

At March 31, 2026, the future minimum annual obligations for the Company’s operating lease liabilities are as follows:

10. Segment Reporting

During fiscal year 2025, in connection with the proposed separation of our operations into two independent, publicly traded companies, our Chief Executive Officer, who is our chief operating decision maker (“CODM”), revised the information he regularly reviews in evaluating the allocation of resources and assessing operating performance. As a result of these changes, we updated our segment reporting to reflecttwo operating segments: Biopharma and Royalty Management. Our Biopharma segment focuses on the development and potential commercialization of innovative immunology therapeutics for autoimmune and inflammatory diseases and our Royalty Management segment manages the financial collaboration for Jemperli with GSK and for imsidolimab with Vanda.

Segment profit or loss is measured as the net loss and is used to monitor results. Our Royalty Management segment revenue consists of non-cash royalties and milestones, and is derived from collaboration agreements. For more information, see Note 4. We do not report identifiable assets by segment as this is not a metric used by our CODM to allocate resources or evaluate performance.

The following tables present our segment information for thethree months ended March 31, 2026 and 2025 and are a summary of segment revenue, loss and our significant expenses. Prior periods have been recast to conform to the newly identified segments (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.

(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.

11. Subsequent Events

On April 20, 2026 (the “Distribution Date”), we completed the previously announced separation (the “Spin-Off”) of First Tracks Biotherapeutics. The Spin-Off of First Tracks Biotherapeutics was achieved through our pro rata distribution of all of the outstanding shares of common stock of First Tracks Biotherapeutics to holders of record of our common stock. Each holder of record of our common stock receivedone share of First Tracks Biotherapeutics’ common stock for every one share of our common stock held on April 6, 2026, the record date for the distribution. On April 20, 2026, First Tracks Biotherapeutics’ shares of common stock began trading on the Nasdaq Stock Market LLC under the ticker symbol “TRAX.”

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 expected future royalty revenues from Jemperli under our collaboration agreement with GSK;

•

the current and future commercial success of Jemperli;

•

the extent and effectiveness of GSK’s development, commercialization, sales, marketing and distribution of Jemperli;

•

the timing of and the ability to obtain and maintain regulatory approvals for our collaborators’ products and product candidates for which we currently receive or may receive royalties;

•

the rate and degree of market acceptance and clinical utility of Jemperliand imsidolimab;

•

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 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;

•

the success, benefits or costs of the recent separation of the Company’s operations into two independent, publicly traded companies; 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.