On December 15, 2025, the Company and Norgine Pharma UK Limited (together with its affiliates in the Norgine group of companies, Norgine) entered into a License Agreement (the Norgine Agreement) under which the Company granted Norgine an exclusive license with respect to commercial rights and certain development rights to the combination of tobevibart, an investigational monoclonal antibody, and elebsiran, an investigational small interfering ribonucleic acid (Licensed Product), for the treatment of people living with chronic hepatitis delta (CHD) in Europe, Australia, and New Zealand (collectively, the Norgine Territory), while Vir Bio will retain commercial rights for the Licensed Product in the United States and all other international markets outside of the People’s Republic of China and Taiwan. The Company and Norgine will collaborate on the development and commercialization of Licensed Product in Norgine Territory under the oversight of various joint committees, with the Company primarily responsible for development activities for the ongoing trials in Vir Bio’s ECLIPSE registrational program (ECLIPSE 1, 2 and 3) and Norgine primarily responsible for regulatory, medical affairs and commercialization activities. Vir Bio will also provide future commercial supply to Norgine. In exchange, Vir Bio received an initial reimbursement of historical development costs from Norgine in the amount of €55 million or $64.3 million in December 2025 and is eligible to receive up to an additional €495 million in clinical, regulatory and sales milestones, along with tiered, mid-teen to high-twenties percent royalties on net sales in the Norgine Territory. In addition, clinical development costs for the ongoing ECLIPSE registrational program will be shared, with Norgine contributing approximately 25% of external costs starting from January 1, 2026.

The Company determined that the Norgine Agreement is a collaborative arrangement given that both parties are (i) active participants in the development and commercialization of Licensed Product in Norgine Territory and (ii) exposed to significant risks and rewards dependent on the commercial success of Licensed Product. The Company further evaluated whether the Norgine Agreement is partially within the scope of ASC 606 and identified two performance obligations, the delivery of Norgine License and the promise to conduct development activities for the ongoing ECLIPSE registrational program. The Norgine License was considered distinct from the development activities as those activities will not significantly modify or customize the Norgine License, in-part due to the late clinical stage of development at contract inception. With respect to the promise to deliver commercial supplies in the future, it is at Norgine’s option and will be provided at fair value, and therefore, it is not considered a material right or a performance obligation under the Norgine Agreement.

With respect to the delivery of Norgine License, the transaction price include the initial payment of €55 million, clinical, regulatory and sales milestones of up to €495 million and sales royalties. The clinical and regulatory milestones are variable considerations and are fully constrained at contract inception. Sales milestones and royalties are variable considerations and will be recognized when future sales occur. The Company will reassess revenue constraints each period. The performance obligation to deliver Norgine License was satisfied upon transfer of the license to Norgine in December 2025. With respect to the promise to conduct development activities and related cost share, the Company will account for the costs shared with Norgine as reduction of research and development expenses in the period when those costs are shared under the Norgine Agreement.

On September 9, 2024 (Acquisition Date), the Company closed the license agreement with Amunix Pharmaceuticals, Inc., a Sanofi company, previously announced on August 1, 2024 (the “Sanofi Agreement). The Sanofi Agreement provides the Company with an exclusive worldwide license to use of the proprietary PRO-XTEN® universal masking technology for oncology and infectious disease, excluding the ophthalmological field, and to three early-stage clinical dual-masked TCEs that all leverage the PRO-XTEN® universal masking platform within a range of oncology indications.

Under the Sanofi Agreement the Company made an upfront payment to Sanofi in the amount of $100.0 million and placed into escrow a $75.0 million milestone payment due to former shareholders of Amunix Pharmaceuticals, Inc., which is subject to VIR-5525 achieving “first in human dosing” by 2026. In July 2025, the first patient was dosed in phase 1 study evaluating VIR-5525. During the third quarter of 2025, the Company paid the $75.0 million milestone, which was recorded as part of research and development expenses in the Company’s consolidated statement of operations for the year ended December 31, 2025.

Sanofi will also be eligible to receive up to an additional $323.0 million in future development and regulatory milestone payments, up to an additional $1.49 billion in commercial net sales-based milestone payments, and low single-digit to low double-digit tiered royalties on worldwide net sales. In addition, if, within a two-year period from the execution of the Sanofi Agreement, the Company executes a transaction that gives rise to Vir Bio receiving certain sublicense income related to the licenses obtained from the Sanofi Agreement, Sanofi may be eligible to receive a portion of such income.

Additionally, as part of the Sanofi Agreement, the Company paid $3.7 million to acquire certain lab equipment and cash deposits primarily related to contract manufacturing agreements. Shortly after the closing of the Sanofi Agreement, the Company hired certain former Sanofi personnel. The Company incurred approximately $4.6 million of transaction costs associated with the closing of the Sanofi Agreement. The following table summarizes the aggregate amount paid for the assets acquired by the Company in connection with the Sanofi Agreement as of the acquisition date (in thousands):

The Company accounted for the Sanofi Agreement as an asset acquisition in accordance ASC 805-50 as substantially all of the fair value of the assets acquired is concentrated in a group of similar identifiable assets. The three early clinical stage oncology TCEs use the same universal PRO-XTEN® masking technology and have similar development timelines, probabilities of risk, and loss of patent exclusivity, among other characteristics. ASC 805-50 requires the acquiring entity in an asset acquisition to recognize assets acquired and liabilities assumed based on the cost to the acquiring entity on a relative fair value basis, which includes consideration given. The total purchase price was allocated to the acquired assets based on their relative fair values as of the Acquisition Date as follows (in thousands):

The fair value of the IPR&D was estimated using a multi-period excess earnings income approach that discounts expected cash flows to present value by applying a discount rate that represents the estimated rate that market participants would require for the intangible asset. The expected cash flows and related discount rate are significant unobservable inputs categorized within Level 3 of the fair value hierarchy. As the three early clinical stage oncology TCEs have not achieved regulatory approval when acquired, the portion of the purchase price allocated to the IPR&D was immediately expensed to research and development expenses as they had no alternative future use. Contingent milestone payments will be recognized when the contingency is resolved and the consideration is paid or becomes payable. Any milestone payments made in the future will either be expensed as research and development or capitalized as a developed asset based on when regulatory approval is obtained. The Company will recognize sales-based milestone and royalty payments in cost of sales as revenue from product sales is recognized. The fair value of the assembled workforce was estimated using a replacement cost method. The assembled workforce is classified as intangible assets, net and is amortized over an expected useful life of five years.

In 2020, the Company, GSK entered into a collaboration agreement (the 2020 GSK Agreement), pursuant to which the Company and GSK agreed to collaborate to research, develop and commercialize products for the prevention, treatment and prophylaxis of diseases caused by SARS-CoV-2, the virus that causes COVID-19, and potentially other coronaviruses. On February 8, 2023, the Company and GSK entered into two amendments to the 2020 GSK Agreement, pursuant to which the Company and GSK agreed to reduce the scope of the collaboration to include only sotrovimab and VIR-7832, and certain variants thereof. The Company retains the right to progress development of vaccine products directed to SARS-CoV-2 and other coronaviruses independently (including with or for third parties) outside the scope of the 2020 GSK Agreement, subject to the payment of tiered royalties to GSK on net sales of any vaccine products covered by certain GSK intellectual property rights in the low single digits. The Company retains the sole right to progress the development and commercialization of the terminated antibody products independently (including with or for third parties), subject to the payment of tiered royalties to GSK on net sales of such terminated antibody products at percentages ranging from the very low single digits to the mid-single digits, depending on the nature of the antibody product being commercialized. The parties share all development costs, manufacturing costs, and costs and expenses for the commercialization of sotrovimab, with the Company bearing 72.5% of such costs, except that GSK has the sole right to develop (including to seek, obtain or maintain regulatory approvals), manufacture and commercialize sotrovimab in and for People’s Republic of China and Taiwan at GSK’s sole cost and expense, and equal sharing of such costs for the functional genomics products.

In May 2021, the U.S. Food and Drug Administration (FDA) granted an emergency use authorization (EUA) in the United States for sotrovimab, the first collaboration product under the Antibody Program. In April 2022, the FDA excluded the use of sotrovimab in all U.S. regions due to the continued proportion of COVID-19 cases caused by certain Omicron subvariants. In December 2024, the FDA revoked EUA granted to sotrovimab.

GSK is the lead party for manufacturing and commercialization of sotrovimab. As the agent, the Company recognizes its contractual share of the profit-sharing amounts as revenue, based on sales net of various estimated deductions such as rebates, discounts, chargebacks, credits and returns, less cost of sales and allowable expenses (including manufacturing, distribution, medical affairs, selling, and marketing expenses) in the period the sale occurs. In periods when allowable expenses exceed amounts recognized for net product sales of sotrovimab, negative revenue is reported in our consolidated statements of operations. The Company’s contractual share of the profit-sharing amounts is subject to potential future adjustments to allowable expenses, which represents a form of variable consideration. At each reporting period, the Company evaluates the latest available facts and circumstances to determine whether any portion of profit-sharing amounts should be constrained. For the year ended December 31, 2023, the Company released $35.7 million profit-sharing amount previously constrained for certain allowable manufacturing expenses related to excess sotrovimab supply and binding reserved manufacturing capacity not utilized.

Costs associated with co-development activities performed under the 2020 GSK Agreement are included in research and development expenses on the consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. Under the 2020 GSK Agreement, the Company recognized additional net research and development expenses of $5.5 million, $7.7 million, and $23.4 million during the years ended December 31, 2025, 2024, and 2023, respectively.

In 2021, the Company and GSK entered into a collaboration agreement (the 2021 GSK Agreement) under which the parties agreed to expand the 2020 GSK Agreement to collaborate on three separate programs. One of three programs granted GSK the option to select up to three non-influenza target pathogens. GSK selected respiratory syncytial virus (RSV) as its first pathogen in 2022. On February 21, 2024, the Company and GSK entered into a letter agreement (the Letter Agreement) pursuant to which the Company and GSK agreed to reduce the scope of collaboration to include only the RSV program. During the first quarter of 2024, the Company recognized $51.7 million deferred revenue as license and collaboration revenue as GSK’s rights to select the remaining up to two additional non-influenza target pathogens expired on March 25, 2024. During the fourth quarter of 2024, the Company opted-out of the RSV program. GSK continues to pursue the development and commercialization of the RSV program unilaterally. If the RSV program is commercialized, GSK will pay to the Company a royalty on net sales at the low single digits.

Costs associated with co-development activities performed under the 2021 GSK Agreement are included in research and development expenses in the consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. During the years ended December 31, 2025 and 2024, the reimbursement of research and development expenses by GSK is not material. During the year ended December 31, 2023, the Company recognized additional net research and development expenses of $2.2 million.

In October 2017, the Company and Alnylam Pharmaceuticals, Inc. (Alnylam) entered into a collaboration and license agreement (the Alnylam Agreement). Under the Alnylam Agreement, the Company obtained a worldwide, exclusive license to develop, manufacture and commercialize siRNA product candidates directed to HBV, including elebsiran, for all uses and purposes including the treatment of hepatitis B virus (HBV) and hepatitis delta virus (HDV). Under the Alnylam Agreement, the Company also held options to obtain similar licenses to siRNA product candidates for up to four other infectious disease targets selected by Vir Bio, but following an amendment and restatement of the Alnylam Agreement in March 2025 (the Restated Alnylam Agreement), those options (and all rights and obligations related to those infectious disease targets) were terminated. At the same time Alnylam elected to not opt-in to the profit-sharing arrangement with respect to any licensed siRNA product candidates, including elebsiran, directed to HBV or HDV. The Company remains solely responsible, at its expense, for conducting all development, manufacture and commercialization activities for elebsiran in HBV and HDV indications, and the Company is required to use commercially reasonable efforts to develop and commercialize elebsiran for the treatment of HBV or HDV in the United States and specified major markets.

In connection with the Restated Alnylam Agreement and Alnylam’s election to not opt-in to the profit-sharing arrangement, the Company paid Alnylam $30.0 million, which was recorded as part of research and development expenses in the Company’s statement of operations for the year ended December 31, 2025. After this payment, the remaining amount of the development and regulatory milestones is up to $145.0 million for elebsiran. Any development and regulatory milestones for elebsiran will be payable to Alnylam only once, irrespective of dosage, formulation forms, route of administration or indication. Following commercialization, the Company will be required to pay to Alnylam up to $250.0 million in the aggregate for the first achievement of specified levels of net sales by elebsiran products directed to HBV, whether for the treatment of HBV or HDV. The Company will also be required to pay Alnylam tiered royalties at percentages ranging from the low double-digits to mid-teens on annual net sales of siRNA products directed to HBV, such as elebsiran, whether for the treatment of HBV or HDV, subject to specified reductions and offsets. The royalties are payable on a product-by-product and country-by-country basis until the later of the expiration of all valid claims of specified patents covering such product in such country and 10 years after the first commercial sale of such product in such country. Alnylam is entitled to receive a portion of any consideration the Company receives as a result of granting a sublicense under the licenses granted to Vir Bio by Alnylam under the Alnylam Agreement.