Vaxcyte, Inc.

Notes to Unaudited Condensed Consolidated Financial Statements

1. Company Organization and Nature of Business

Vaxcyte, Inc. (“we,” “our,” “us,” “Vaxcyte” and the “Company”) refers to Vaxcyte, Inc., a Delaware corporation, and our wholly-owned consolidated subsidiary, or as the context may require, Vaxcyte, Inc. only. We are headquartered in San Carlos, California, and were incorporated in the state of Delaware on November 27, 2013 as SutroVax, Inc., and changed our name to Vaxcyte, Inc. on May 15, 2020. We are a clinical-stage vaccine innovation company engineering high-fidelity vaccines to protect humankind from the consequences of bacterial diseases. We are re-engineering the way highly complex vaccines are made through the XpressCF™ cell-free protein synthesis platform. Unlike conventional cell-based approaches, our system for producing difficult-to-make proteins and antigens is intended to develop and deliver high-fidelity vaccines with enhanced immunological benefits that are beyond the capabilities of conventional approaches.

Our primary activities since incorporation have been to perform research and development, undertake preclinical and clinical studies and conduct manufacturing activities in support of our product development and commercial readiness efforts; organize and staff our Company; establish our intellectual property portfolio; and raise capital to support and expand such activities.

2. Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

These condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and footnote disclosures normally included in the condensed consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted in accordance with such rules and regulations.

The condensed consolidated financial statements include the Company and its wholly owned subsidiary. All intercompany transactions and balances have been eliminated upon consolidation.

Unaudited Interim Condensed Consolidated Financial Statements

The condensed consolidated balance sheets as of March 31, 2026, the condensed consolidated statements of operations, comprehensive loss and stockholders’ equity for the three months ended March 31, 2026 and 2025 and the condensed consolidated statements of cash flows for the three months ended March 31, 2026 and 2025 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair statement of our financial information. The financial data disclosed in the footnotes to the condensed consolidated financial statements related to the three months ended March 31, 2026 and 2025 are also unaudited. The results of operations for the three months ended March 31, 2026 are not necessarily indicative of the results to be expected for the year ending December 31, 2026 or for any other future annual or interim period. These interim condensed consolidated financial statements should be read in conjunction with our audited consolidated financial statements and related notes thereto for the year ended December 31, 2025 included in our Annual Report on Form 10-K filed with the SEC on February 24, 2026.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements. On an ongoing basis, we evaluate our estimates and assumptions, including those related to stock-based compensation expense, accruals for certain research and development costs, the valuation of deferred tax assets and income taxes. Management bases our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates.

Summary of Significant Accounting Policies

There have been no material changes to our significant policies as of and for the three months ended March 31, 2026 from our Annual Report on Form 10-K for the fiscal year ended December 31, 2025.

Recently Issued Accounting Standards Not Yet Adopted

In November 2024, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40), (“ASU 2024-03”). The amendments in ASU 2024-03 intend to improve the disclosures about a public business entity’s expenses and address requests from investors for more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation, amortization, and depletion). This new guidance is effective for us for the annual periods beginning after December 15, 2026. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures.

In September 2025, the FASB issued ASU No. 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software, (“ASU 2025-06”). The amendments in ASU 2025-06 intend to modernize the accounting for software costs that are accounted for under Subtopic 350-40, Intangibles—Goodwill and Other—Internal-Use Software (referred to as “internal-use software”). This new guidance is effective for us for the annual periods beginning after December 15, 2027. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures.

In December 2025, the FASB issued ASU 2025-10, Government Grants (Topic 832): Accounting for Government Grants Received by Business Entities. The amendments in ASU 2025-10 intend to establish authoritative guidance on the accounting for government grants received by business entities. This guidance is effective for us beginning with our 2029 fiscal year annual reporting period, with early adoption permitted. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures.

In December 2025, the FASB issued ASU 2025-11 to amend the guidance in “Interim Reporting” (Topic 270). The update provides clarifications intended to improve the consistency and usability of interim disclosure requirements, including a comprehensive listing of required interim disclosures and a new disclosure principle for reporting material events occurring after the most recent annual period. The amendments do not change the underlying objectives of interim reporting but are designed to enhance clarity in application. The guidance is effective for fiscal years beginning after December 15, 2027, including interim periods within those fiscal years. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures.

In December 2025, the FASB issued ASU 2025-12 “Codification Improvements” to address suggestions received from stakeholders on the Accounting Standards Codification ("the Codification") and to make other incremental improvements to U.S. GAAP. The update represents changes to the Codification that (i) clarify, (ii) correct errors, or (iii) make minor improvements. The amendments make the Codification easier to understand and apply. The guidance is effective for fiscal years beginning after December 15, 2026, including interim periods within those fiscal years. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures.

3. Fair Value Measurements and Fair Value of Financial Instruments

The following tables set forth our financial instruments measured at fair value on a recurring basis by level within the fair value hierarchy at March 31, 2026 and December 31, 2025:

We had no Level 3 securities either as of March 31, 2026 or 2025.

There wereno transfers within the hierarchies during the three months ended March 31, 2026.

As of March 31, 2026 and December 31, 2025, we had investments with a total fair market value of $1.6 billion and $0.3 billion, respectively, in an unrealized loss position, of which $491.9 million and $120.2 million, respectively, were in a continuous unrealized loss position for more than 12 months. As of March 31, 2026, the gross unrealized losses of securities that have been in a continuous unrealized loss position was $4.9 million, of which $4.4 million related to securities that have been in a continuous unrealized loss position for less than 12 months. As of December 31, 2025, the gross unrealized losses of securities that have been in a continuous unrealized loss position was immaterial.

Unrealized losses related to our investments are primarily due to interest rate fluctuations as opposed to credit quality. We do not intend to sell any of the securities in an unrealized loss position and it is not likely that we would be required to sell these securities before recovery of their amortized cost basis, which may be at maturity. We did not recognize any credit losses related to our investments during the three months ended March 31, 2026 or 2025.

The following table presents the contractual maturities of our investments as of March 31, 2026 (in thousands):

4. Commercial Manufacturing and Supply Agreements

Lonza Ltd. (“Lonza”)

In October 2023, we entered into a pre-commercial services and commercial manufacturing supply agreement with Lonza (the “Lonza Commercial Manufacturing and Supply Agreement”).

Pursuant to the Lonza Commercial Manufacturing and Supply Agreement, Lonza will (i) construct and build out a dedicated suite (the “Suite”) at Lonza’s facilities in Visp, Switzerland to manufacture certain key components (including drug substance) for our proprietary pneumococcal conjugate vaccine (“PCV”) franchise and any other products or intermediates we may choose (collectively, the “Products”) and (ii) maintain and operate the Suite (utilizing Lonza’s employees) to manufacture the Products as a service provided to us, including conducting related quality control and quality assurance operations. Lonza will be a preferred, non-exclusive, supplier of the Products to us, and we retain the right to procure the Products from one or more alternate and/or backup manufacturers of the Products (including at our own facilities).

Under the Lonza Commercial Manufacturing and Supply Agreement, prior to completion of construction and certification of the Suite for commercial operation, we will contribute to the capital expenditure costs to construct the Suite (and will own certain equipment in the Suite to be purchased or otherwise acquired by us), and will pay Lonza a fixed-rate monthly service fee for Lonza’s pre-commercial services prior to commencement of commercial operations (which monthly service fee amount is subject to increases in subsequent years). Following commencement of commercial operations of the Suite to manufacture the Products, we will pay Lonza (i) Suite fees based on allocations of certain of Lonza’s costs to maintain the facility in which the Suite is located and to provide shared services to us and Lonza’s other customers in such facility, (ii) service fees based upon Lonza’s actual full-time equivalent employee (“FTE”) costs to operate the Suite to manufacture the Products, and (iii) certain other pass-through costs, including for raw materials. In addition, we may be obligated to pay or reimburse Lonza for certain other fees and expenses under the Lonza Commercial Manufacturing and Supply Agreement. Lonza will be eligible for certain financial bonuses, and subject to certain financial penalties, as incentives for the timely completion of certain scale-up activities, receipt of certain regulatory approvals for the Suite and manufacture of the Products in accordance with our commercial requirements.

Unless earlier terminated, the Lonza Commercial Manufacturing and Supply Agreement will remain in effect until December 31, 2038, subject to automatic renewal for up tothree additional renewal periods offive years each, unless we elect not to renew (with 24 months advanced notice to Lonza). We are permitted to terminate the Commercial Manufacturing and Supply Agreement for convenience or for Lonza’s uncured material breach, in each case subject to certain notice obligations. Lonza is permitted to terminate the Lonza Commercial Manufacturing and Supply Agreement in the event that we commit certain specified material breaches, including uncured failure to pay material and undisputed amounts of money due to Lonza, subject to certain notice obligations. Either party may terminate the Commercial Manufacturing and Supply Agreement in certain circumstances in the event of the other party’s bankruptcy. In the event that we terminate the agreement for convenience, or Lonza terminates the agreement in the event that we commit certain specified material breaches, then certain termination consequences may be triggered, including that (i) we would forfeit any outstanding entitlement to credit from Lonza of the Repurposing Fee (as defined below), and (ii) we would be obligated to pay Lonza a termination penalty equal to the greater of (a) CHF 70.0 million, or (b) a prespecified number of months’ FTE fees for the actual FTEs assigned to us as of the date of termination. Within 30 days of the Effective Date, we paid Lonza a repurposing fee (the “Repurposing Fee”) of CHF 27.0 million that will be credited back to us over a 10-year period starting upon commencement of commercial production. In the event of a termination under certain circumstances, Lonza shall be obligated to provide certain wind-down and transition services to us for up to 12 months and 24 months, respectively.

As of March 31, 2026 and 2025, we have incurred $218.9 million and $171.3 million of capital expenditures related to the Vaxcyte owned facility buildout and equipment, respectively. In addition, as of March 31, 2026 and 2025, we have incurred $155.1 million and $74.7 million of facility buildout expenditures that are owned and controlled by Lonza, including the Repurposing Fee, and costs associated with certification of the Suite for commercial operation, respectively. These amounts have been accounted for as prepaid lease payments and will be recorded as a ROU asset under Accounting Standards Codification (“ASC”) 842 lease accounting when control over the Suite is transferred to us, which we expect to occur upon the completion of construction and certification of the Suite for commercial operation.

Thermo Fisher Scientific

In September 2025, we entered into a master services agreement with Patheon Manufacturing Services LLC, part of Thermo Fisher Scientific (collectively, “Thermo Fisher”), pursuant to which Thermo Fisher will formulate, fill, inspect, package, label, test, manufacture and supply drug product for us at its facility in Greenville, North Carolina (the "Thermo Fisher Commercial Manufacturing and Supply Agreement"). Pursuant to the Thermo Fisher Commercial Manufacturing and Supply Agreement, we have agreed to order drug product from Thermo Fisher based on certain binding forecast periods and established prices. In addition, we will also pay Thermo Fisher for technology transfer activities and reimburse Thermo Fisher for certain out-of-pocket capital expenditures under the terms of the agreement.

The Thermo Fisher Commercial Manufacturing and Supply Agreement has an initial term of 15 years and will automatically renew for additional three-year periods unless either party provides notice of non-renewal before the end of the then existing term, subject to completion of ongoing services. We are permitted to terminate the Thermo Fisher Commercial Manufacturing and Supply Agreement prior to expiration, subject to the payment of applicable termination fees, plus certain capital expenditure commitments.

5. Leases

Operating Lease Obligations

Office Facility

In January 2021, we entered into a lease agreement (the “Original Lease”) for our current corporate headquarters facility located in San Carlos, California (the “Headquarters Facility”). The lease term began on December 3, 2021, as amended on October 17, 2023, and was set to expire on December 31, 2025.

In September 2023, we entered into an assignment and assumption of lease agreement (the “Assignment Agreement”) for an expanded lease space in the same building as our Headquarters Facility (the “Assumed Lease Premises”). The assumed lease had an original contractual term of 10 years, set to expire on November 30, 2031. Pursuant to the Assignment Agreement, the base rent was abated for three full calendar months following the October 1, 2023 effective date of the Assignment Agreement. Thereafter, we were obligated to pay an aggregate of approximately $1.9 million in rent payments for the remaining nine months of the first year, with a 3% rent adjustment (not inclusive of rent abatement) every year thereafter.

In November 2024, we amended and restated the Original Lease (the “Amended and Restated Lease”) as a single, unified lease for our Headquarters Facility which includes the existing space under the Original Lease and the Assumed Lease Premises (collectively, the “Existing Premises”) and expanded space covering additional floors (the “Additional Premises”), which resulted in a lease modification in accordance with ASC 842. The Amended and Restated Lease has an initial contractual term of 10 years, contains rent-free periods, scheduled rent increases, lease incentives and the option oftwo consecutive rights to extend the term for 60 months each. The effective date of the Amended and Restated Lease was

November 15, 2024 which, for the purposes of lease accounting, is the commencement date of the lease of the Existing Premises. The commencement dates of the Additional Premises occur when certain leasehold improvements and specifications are substantially complete, the first, second and third of which occurred in February 2025, November 2025 and December 2025, respectively, and the last of which is estimated to occur in third quarter of 2026. Our Amended and Restated Lease expires on February 28, 2035.

In November 2024, we entered into a sublease agreement, for which we are the sublessor, for a portion of our Existing Premises. This sublease has a contractual term oftwo years, expiring on December 31, 2026, unless earlier terminated, withtwo conditional options to extend the term of the sublease for a period of 12 months each. The commencement date of this sublease was December 12, 2024.

In July 2024, we entered into a sublease agreement, for which we are the sublessee for a new operating lease in the same campus as our corporate headquarters. This sublease has rent-free periods, scheduled rent increases, and a contractual term oftwo years, expiring on June 30, 2026, unless earlier terminated.

Manufacturing Facility

In October 2023, we entered into the Lonza Commercial Manufacturing and Supply Agreement. We have concluded that this agreement contains an embedded lease and will be accounted for in accordance with ASC 842 upon the commencement date. As of March 31, 2026, the lease had not commenced and, as such, no lease liability or ROU asset was recorded on the condensed consolidated balance sheets andno operating lease expense was recorded on the condensed consolidated statements of operations. See Note 4, “Commercial Manufacturing and Supply Agreement”, for further details.

The following tables present additional information for our operating leases:

Maturities of lease liabilities as of March 31, 2026 were as follows:

Rent expense recognized under the leases was $5.5 million and $3.6 million for the three months ended March 31, 2026 and 2025, respectively.

6. Commitments and Contingencies

Legal Contingencies

From time to time, we may become involved in legal proceedings arising from the ordinary course of business. We record a liability for such matters when it is probable that future losses will be incurred and that such losses can be reasonably estimated. Significant judgment by us is required to determine both probability and the estimated amount. We do not believe that there is any litigation or asserted or unasserted claim pending that could, individually or in the aggregate, have a material adverse effect on our results of operations or financial condition.

Guarantees and Indemnifications

In the normal course of business, we enter into agreements that contain a variety of representations and provide for general indemnification. Our exposure under these agreements is unknown because it involves claims that may be made against us in the future. To date, we have not paid any claims or been required to defend any action related to our indemnification obligations. As of March 31, 2026, we did not have any material indemnification claims that were probable or reasonably possible and consequently have not recorded related liabilities.

To the extent permitted under Delaware law, we have agreed to indemnify our directors and officers for certain events or occurrences while the director or officer is, or was, serving at our request in such capacity. The indemnification period covers all pertinent events and occurrences during the director’s or officer’s service. The maximum potential amount of future payments we could be required to make under these indemnification agreements is not specified in the agreements; however, we have directors and officers insurance coverage that reduces our exposure and enables us to recover a portion of any future amounts paid. We have not incurred any material costs as a result of such indemnification and are not currently aware of any indemnification claims.

Development and Manufacturing Services Agreements with Lonza

In April 2022, we entered into a non-exclusive development and manufacturing services agreement with Lonza effective as of March 22, 2022, which was subsequently amended in May 2022, November 2022 and October 2023 (as amended, the “2022 Lonza DMSA”). Pursuant to the 2022 Lonza DMSA, Lonza is obligated to perform services including manufacturing process development and clinical manufacture and supply of our proprietary PCV candidates.

In February 2023, we entered into another non-exclusive development and manufacturing services agreement with Lonza effective as of March 1, 2023 (the “2023 Lonza DMSA”). Pursuant to the 2023 Lonza DMSA, Lonza will perform manufacturing process development and the manufacture of components for our PCV candidates, including the polysaccharide antigens, our proprietary eCRM protein carrier and conjugated drug substances.

Under each of the 2022 Lonza DMSA and 2023 Lonza DMSA (collectively, the “Lonza Agreements”), we pay Lonza agreed-upon fees for their performance of development and manufacturing services and pass-through expenses incurred by Lonza for raw materials, as well as customary procurement and handling fees.

In February 2026, we entered into another non-exclusive development and manufacturing services agreement with Lonza effective as of January 1, 2026 (the "2026 Lonza DMSA"). Pursuant to the 2026 Lonza DMSA, Lonza will perform manufacturing process development and commercial manufacture and supply of certain key components for our propriety PCV franchise.

Under the 2026 Lonza DMSA, we will pay Lonza for development and manufacturing services, in addition to paying for certain raw material and other costs. We will be required to purchase, and Lonza will be required to supply, the components pursuant to the relevant purchase orders under the agreement. In consideration of the commercial supply services and Lonza’s other obligations under the agreement, we will pay Lonza a daily fee for Lonza’s operation of the facility solely to actively manufacture the components. With respect to such commercial supply, and subject to termination rights, we and Lonza have agreed to a mutually binding percentage of annual facility capacity that shall be utilized by Lonza fully and exclusively for Lonza’s performance of services thereunder, which percentages may be adjusted under certain circumstances.

For additional information about the Lonza Agreements, see “Certain Significant Relationships—Lonza—Development and Manufacturing Services Agreements” included in Part I, Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations of this Quarterly Report on Form 10-Q.

Commercial Manufacturing and Supply Agreements

For details of the Commercial Manufacturing and Supply Agreements with Lonza and Thermo Fisher, see Note 4.

Sutro Option Agreement

In December 2022, we entered into an option agreement with Sutro Biopharma (the “Option Agreement”). Pursuant to the Option Agreement, we acquired from Sutro Biopharma (i) authorization to enter into an agreement with an independent alternate CMO to directly source Sutro Biopharma’s cell-free extract, allowing us to have direct oversight over financial and operational aspects of the relationship with the CMO; and (ii)a right, but not an obligation, to obtain certain exclusive rights to internally manufacture and/or source extract from certain CMOs and the right to independently develop and make improvements to extract (including the right to make improvements to the extract manufacturing process as well as cell lines) for use in connection with the exploitation of certain vaccine compositions(the “Option”). We and Sutro Biopharma agreed to negotiate the terms and conditions of a form definitive agreement to be entered into in the event we exercised the Option, which would include the terms and conditions set forth in an executed term sheet between us (the “Term Sheet”) and such terms that were necessary to give effect to each of the terms and conditions set forth in the Term Sheet (the “Form Definitive Agreement”).

As consideration for the Option and other rights and authorizations granted to us under the Option Agreement, we paid Sutro Biopharma upfront consideration of $22.5 million, consisting of (i) $10.0 million in cash and $7.5 million worth of shares of our common stock (the number of shares calculated based on the arithmetic average of the daily volume weighted average price of our common stock as traded on Nasdaq in the three consecutive trading days immediately prior to the issuance thereof) in December 2022, and (ii) $5.0 million in October 2023 within five business days after we and Sutro Biopharma mutually agreed in writing upon the Form Definitive Agreement on September 28, 2023. The 167,780 shares of common stock issued was recorded at fair value of $8.0 million on the date of settlement, December 22, 2022.

In November 2023 (the “Option Exercise Date”), we exercised the Option by submitting written notice thereof to Sutro Biopharma and concurrently paid Sutro Biopharma $50.0 million in cash as the first of two installment payments for the Option exercise price, followed by the second and final installment of $25.0 million in cash in May 2024. We determined there was no current alternative future use of the acquired manufacturing rights from the Option Agreement and, as a result, the amounts paid were expensed as incurred. Upon the occurrence of certain regulatory milestones, we agreed to pay Sutro Biopharma certain additional milestone payments totaling up to $60.0 million in cash. In the event that we undergo a change of control, certain rights and payments may be accelerated. No milestone payments were made during the three months ended March 31, 2026.

Manufacturing Rights Agreement with Sutro Biopharma

Concurrent with the payment of the first installment of the Option exercise price pursuant to the Option Agreement, in November 2023, the manufacturing rights agreement (in the form of the Form Definitive Agreement) between us and Sutro Biopharma (the “Manufacturing Rights Agreement”) became effective. Pursuant to the Manufacturing Rights Agreement, we obtained exclusive rights to independently, or through certain third parties, develop, improve and manufacture cell-free extract for use in connection with our vaccine candidates.

For additional information about the Manufacturing Rights Agreement, see “Certain Significant Relationships—Sutro Biopharma—Manufacturing Rights Agreement with Sutro Biopharma” included in Part I, Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations of this Quarterly Report on Form 10-Q.

Purchase Commitments

We enter into agreements in the normal course of business with CMOs and other vendors for manufacturing services and raw materials purchases. We rely on several third-party manufacturers for our manufacturing requirements. As of March 31, 2026, we had the following amounts of non-cancelable purchase commitments related to manufacturing services and raw materials purchased due to our key manufacturing partners. These amounts represent our minimum contractual obligations, including termination fees. If we terminate certain firm orders with key manufacturing partners, we will be required to pay for the manufacturing services scheduled or raw materials purchased under our arrangements. The actual amounts we pay in the future to our vendors under such agreements may differ from the purchase order amounts.

7. Stockholders' Equity

Common Stock

Our certificate of incorporation authorizes us to issue up to 500,000,000 shares of common stock with $0.001 par value per share, of which 144,314,981 and 131,058,858 shares were issued and outstanding as of March 31, 2026 and December 31, 2025, respectively. The holders of our common stock are also entitled to receive dividends whenever funds are legally available, when and if declared by our Board. As of March 31, 2026 and 2025, no dividends have been declared.

ATM Program

In July 2021, we entered into an Open Market Sales Agreement SM (the “Original ATM Sales Agreement”) with Jefferies LLC (“Jefferies”) to issue and sell, from time to time at our discretion, shares of our common stock at an aggregate offering price up to $150.0 million through Jefferies acting as our sales agent or principal. As of February 27, 2023, we had sold 4,995,709 shares of our common stock under the Original ATM Sales Agreement at a weighted average price of $27.57 per share for aggregate gross proceeds of $137.8 million. On February 27, 2023, we and Jefferies entered into an amendment to the Original ATM Sales Agreement (as amended, the “Amended ATM Sales Agreement”) to offer and sell additional shares of our common stock with an aggregate offering price up to another $400.0 million, which was in addition to the $150.0 million aggregate offering price under the Original ATM Sales Agreement. Effective as of February 24, 2026, we terminated the Amended ATM Sales Agreement. Prior to termination, we sold 4,211,367 shares of our common stock under the Amended ATM Sales Agreement at a weighted average price of $64.19 per share for aggregate gross proceeds of $270.3 million, or $264.2 million net of commissions and offering expenses. The gross proceeds of the shares sold net of commission and related offering expenses are reflected as an addition to common stock and additional paid-in capital on our condensed consolidated balance sheets.

On February 24, 2026, we entered into a Sales Agreement (the "2026 ATM Sales Agreement") with Leerink Partners LLC ("Leerink Partners"), to issue and sell, from time to time at our discretion, shares of our common stock at an aggregate offering price up to $500.0 million through Leerink Partners as our sales agent. As of March 31, 2026, we have not sold any shares of our common stock under the 2026 ATM Sales Agreement.

Underwritten Follow-on Public Offerings

From January 2022 through September 2024, we successfully completed a number of underwritten public offerings, which included pre-funded warrants to purchase a total of 10,458,434 shares of our common stock. The pre-funded warrants are exercisable, at the option of each holder, in whole or in part by delivering to us a duly executed exercise notice and payment of the exercise price. Each pre-funded warrant has an exercise price of $0.001 per share. No fractional shares of common stock will be issued in connection with the exercise of a pre-funded warrant. The holders of the pre-funded warrants may also satisfy their obligation to pay the exercise price through a “cashless exercise,” in which the holder receives the net value of the pre-funded warrant in shares of common stock determined according to the formula set forth in the pre-funded warrant.

The pre-funded warrants will not expire until they are fully exercised. However, we may not effect the exercise of any pre-funded warrants, and a holder will not be entitled to exercise any portion of any pre-funded warrants that, upon giving effect to such exercise, would cause: (i) the aggregate number of shares of our common stock beneficially owned by such holder (together with affiliates) to exceed 4.99% or 9.99% of the number of shares of our common stock outstanding immediately after giving effect to the exercise, as applicable; or (ii) the combined voting power of our securities beneficially owned by such holder (together with its affiliates) to exceed 4.99% or 9.99% of the combined voting power of all of our securities outstanding immediately after giving effect to the exercise, as applicable, as such percentage ownership is determined in accordance with the terms of the pre-funded warrants. However, any holder of a pre-funded warrant may increase or decrease such percentage to any other percentage not in excess of 19.99% upon at least 61 days' prior notice for the holder to us.

During the three months ended March 31, 2025,3,500,000 shares underlying the pre-funded warrants were exercised to receive 3,499,959 shares of common stock, net of exercise costs. No shares underlying the pre-funded warrants were exercised during the three months ended March 31, 2026. As of both March 31, 2026 and December 31, 2025, a total of 5,463,793 shares underlying pre-funded warrants were outstanding.

In February 2026, we completed an underwritten public offering of 12,650,000 shares of our common stock, which included the full exercise of the underwriters' option to purchase an additional 1,650,000 shares, at a price of $50.00 per share. In aggregate, we received $601.8 million in net proceeds after deducting underwriting discounts, commissions and other offering expenses payable by us.

8. Equity Incentive Plans

Equity Incentive Plans

We currently grant stock options and restricted stock units (“RSUs”) under the 2020 Equity Incentive Plan (“2020 Plan”), which became effective in June 2020 and replaced our 2014 Equity Incentive Plan (“2014 Plan”).

Effective January 1, 2026, the number of shares of common stock available under the 2020 Plan increased by 6,552,942 shares pursuant to the evergreen provision of the 2020 Plan. As of March 31, 2026, an aggregate of 13,718,437 shares of common stock were available for issuance under the 2020 Plan.

Our 2014 Plan permitted the granting of incentive stock options, non-statutory stock options, restricted stock and other stock-based awards. Subsequent to the adoption of the 2020 Plan, no additional equity awards can be made under the 2014 Plan. As of March 31, 2026,838,806 shares and 14,310,030 shares of common stock were subject to outstanding options and RSUs under the 2014 Plan and 2020 Plan, respectively.

Stock Option Activity

Stock option activity under our 2020 Plan, including performance contingent stock options (“PCSOs”), and 2014 Plan, which excludes options to purchase 29,638 shares granted outside of the 2020 Plan and 2014 Plan, was as follows:

During the three months ended March 31, 2026 and 2025, options to purchase 366,253 and 440,454 shares, respectively, were exercised for cash at a weighted-average price per share of $25.00 and $13.97, respectively. The intrinsic value of the stock options exercised was $10.5 million and $31.0 million for the three months ended March 31, 2026 and 2025, respectively. The weighted-average grant date fair value of options granted for the three months ended March 31, 2026 and 2025 was $35.69 and $46.04, respectively.

Stock Unit Award Activity

Stock unit award activity, including performance based stock units (“PSUs”), for the three months ended March 31, 2026 was as follows:

The weighted-average grant date fair value of RSUs granted during the three months ended March 31, 2026 and 2025 was $59.94 and $73.57, respectively. The aggregate intrinsic value of unvested RSUs is calculated using the closing price of our common stock on the grant date.

Shares Available for Grant

Shares available for grant under our 2020 Plan for the three months ended March 31, 2026 were as follows:

2020 Employee Stock Purchase Plan

Effective January 1, 2026, the number of shares of common stock available under the 2020 Employee Stock Purchase Plan (the "2020 ESPP") increased by 1,310,588 shares pursuant to the evergreen provision of the 2020 ESPP. As of March 31, 2026, there were 3,329,946 shares available under the 2020 ESPP.

Stock-based Compensation

The following assumptions were used in the Black-Scholes options pricing model for stock options granted in the respective period of:

We recorded total stock-based compensation expense for the three months ended March 31, 2026 and 2025 related to the 2014 Plan, the 2020 Plan and the 2020 ESPP in the condensed consolidated statements of operations and allocated the amounts as follows:

As of March 31, 2026, there was $351.3 million of unrecognized stock-based compensation expense related to unvested employee and non-employee awards, which is expected to be recognized over a weighted-average period of 2.74 years.

9. Funding Arrangements

Our vaccine development program for VAX-A1, a novel conjugate vaccine candidate designed to prevent disease caused by Group A Streptococcus, has been funded in part by a grant obtained from Combating Antibiotic Resistant Bacteria Biopharmaceutical Accelerator (“CARB-X”), a global non-profit partnership dedicated to accelerating antibacterial innovation to tackle the rising global threat of drug-resistant bacteria. The CARB-X grant provided funding of $11.7 million upon the achievement of VAX-A1 development milestones through June 2024. As of the second quarter of 2024, all of these milestones had been successfully achieved, and no further amounts will be funded under this CARB-X grant.

Our vaccine development program for VAX-GI, a novel preclinical vaccine candidate being developed as a preventative treatment for dysentery and shigellosis, which is caused by Shigella bacteria, is currently funded in part by two grants obtained from the National Institutes of Health (“NIH”) administered by the University of Maryland, Baltimore. Our first grant from the NIH was awarded in April 2021 and provides for potential funding up tofive years totaling approximately $0.5 million. In June 2023, we received another grant from the NIH that provides for potential funding up tofive years totaling approximately $4.6 million. As of March 31, 2026, we have received and expect to continue to receive funding under each of these grants.

We are currently working on a discovery program with the University of North Carolina at Chapel Hill and the University of Chicago to develop a vaccine candidate for the prevention of Chlamydia, which is funded in part by a grant from the National Institute of Allergy and Infectious Diseases that provides potential funding up tofive years totaling approximately $9.5 million. As of March 31, 2026, we have received and expect to continue to receive funding under this grant.

Income from grants is recognized in the period during which the related specified expenses are incurred, provided that the conditions under which the grants were provided have been met. The amount of grant income wasnot material during the three months ended March 31, 2026 and March 31, 2025. The grant receivable related to unreimbursed, eligible costs incurred under the agreements recorded within prepaid expenses and other current assets in the condensed consolidated balance sheets wasimmaterial as of March 31, 2026 and December 31, 2025.

10. Net Loss Per Share

The following table sets forth the computation of basic and diluted net loss per share and excludes shares which are outstanding, but subject to repurchase by us:

The following potentially dilutive securities were excluded from the computation of diluted net loss per share for the period presented because including them would have been antidilutive:

11. Income Taxes

In determining quarterly provisions for income taxes, we use the annual estimated effective tax rate applied to the actual year-to-date profit or loss, adjusted for discrete items arising in that period. Our annual estimated effective tax rate differs from the U.S. federal statutory rate primarily as a result of changes in our valuation allowance against our deferred tax assets. During the three months ended March 31, 2026 and 2025, we incurred net pre-tax losses in the jurisdictions we operate in and hadno income tax provisions. During the three months ended March 31, 2026, there were no material changes to our unrecognized tax benefits, and we do not expect to have any significant changes to unrecognized tax benefits through the end of the fiscal year. We do not have any tax audits or other issues pending.

12. Segment Reporting

We operate and manage our business asone reportable and operating segment. Our chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance based on consolidated net loss, as is reported in our condensed consolidated statements of operations.

Our long-lived assets are based in the United States and Switzerland. Long-lived assets are comprised of property and equipment. As of March 31, 2026 and December 31, 2025, property and equipment based in the United States was $41.3 million and $39.7 million, respectively. As of March 31, 2026 and December 31, 2025, property and equipment based in Switzerland was $219.4 million and $217.7 million, respectively.

This following table presents segment operation results for the three months ended March 31, 2026 and 2025:

(1)Research and development - external costs consist primarily of product and clinical development, research, facility, depreciation, professional and consulting services expenses attributed to the research and development departments.

(2)Research and development - internal costs consist of internal employee costs including stock-based compensation expenses.