FULLTEXT DEL 1 AV 5
10-K – 2026-02-06 – biib-20251231.htm
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biib:ReportableSegmentMember 2023-01-01 2023-12-31 0000875045 biib:MarketedProductsMember biib:ReportableSegmentMember 2025-01-01 2025-12-31 0000875045 biib:MarketedProductsMember biib:ReportableSegmentMember 2024-01-01 2024-12-31 0000875045 biib:MarketedProductsMember biib:ReportableSegmentMember 2023-01-01 2023-12-31 0000875045 us-gaap:ServiceOtherMember biib:ReportableSegmentMember 2025-01-01 2025-12-31 0000875045 us-gaap:ServiceOtherMember biib:ReportableSegmentMember 2024-01-01 2024-12-31 0000875045 us-gaap:ServiceOtherMember biib:ReportableSegmentMember 2023-01-01 2023-12-31 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2025 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission file number: 0-19311 BIOGEN INC. (Exact name of registrant as specified in its charter) Delaware 33-0112644 (State or other jurisdiction of incorporation or organization) (I.R.S. Employer Identification No.) 225 Binney Street , Cambridge , MA 02142 ( 617 ) 679-2000 (Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices) Securities registered pursuant to Section 12(b) of the Act: Title of Each Class Trading Symbol(s) Name of Each Exchange on Which Registered Common Stock, $0.0005 par value BIIB The Nasdaq Global Select Market Securities registered pursuant to Section 12(g) of the Act: None Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes x No o Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o No x Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No o Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes x No o Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and "emerging growth company" in Rule 12b-2 of the Exchange Act. Large accelerated filer x Accelerated filer ☐ Non-accelerated filer ☐ Smaller reporting company ☐ Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. x If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐ Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐ Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes ☐ No x The aggregate market value of the registrant’s common stock held by non-affiliates of the registrant (without admitting that any person whose shares are not included in such calculation is an affiliate) computed by reference to the price at which the common stock was last sold as of the last business day of the registrant’s most recently completed second fiscal quarter was $ 18,378,285,308 . As of February 4, 2026, the registrant had 146,758,528 shares of common stock, $0.0005 par value, outstanding. DOCUMENTS INCORPORATED BY REFERENCE Portions of the definitive proxy statement for our 2026 Annual Meeting of Stockholders are incorporated by reference into Part III of this report. Table of Contents BIOGEN INC. ANNUAL REPORT ON FORM 10-K For the Year Ended December 31, 2025 TABLE OF CONTENTS Page PART I Item 1. Business 1 Item 1A. Risk Factors 39 Item 1B. Unresolved Staff Comments 54 Item 1C. Cybersecurity 54 Item 2. Properties 55 Item 3. Legal Proceedings 56 Item 4. Mine Safety Disclosures 56 PART II Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities 57 Item 6. Reserved 58 Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations 59 Item 7A. Quantitative and Qualitative Disclosures About Market Risk 93 Item 8. Financial Statements and Supplementary Data 94 Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure 94 Item 9A. Controls and Procedures 94 Item 9B. Other Information 95 Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections 95 PART III Item 10. Directors, Executive Officers and Corporate Governance 96 Item 11. Executive Compensation 96 Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters 96 Item 13. Certain Relationships and Related Transactions, and Director Independence 96 Item 14. Principal Accountant Fees and Services 96 PART IV Item 15. Exhibits and Financial Statement Schedules 97 Item 16. Form 10-K Summary 97 Signatures 100 Consolidated Financial Statements F- 1 Table of Contents NOTE REGARDING FORWARD-LOOKING STATEMENTS This report contains forward-looking statements that are being made pursuant to the provisions of the Private Securities Litigation Reform Act of 1995 (the PSLRA) with the intention of obtaining the benefits of the “Safe Harbor” provisions of the PSLRA. These forward-looking statements may be accompanied by such words as “aim,” “anticipate,” "assume," “believe,” “contemplate,” “continue," "could," “estimate,” “expect,” “forecast,” “goal,” “guidance,” “hope,” “intend,” “may,” “objective,” "outlook," “plan,” “possible,” "potential," “predict,” “project,” “should,” “target,” “will,” “would” or the negative of these words or other words and terms of similar meaning. Given their forward-looking nature, these statements involve substantial risks and uncertainties and may be based on inaccurate assumptions. This report includes, among others, forward-looking statements regarding: • our expected financial and operating performance; • our long-term strategy and supporting business plans, including our product pipeline; • our expectations about growth through acquisitions and key collaborative relationships and funding arrangements; • our belief that our long-term competitive position depends upon our success in discovering and developing innovative, cost-effective products that serve unmet medical needs, along with our ability to manufacture products efficiently and to launch and market them effectively in a highly competitive environment; • our ability to obtain and maintain adequate coverage, pricing and reimbursement from third-party payors and governments; • our expectations regarding certain legal and regulatory proceedings and investigations; and • our belief that our existing funds, when combined with cash generated from operations and our access to additional financing resources, if needed, are sufficient to satisfy our operating, working capital, strategic alliance, milestone payment, capital expenditure and debt service requirements for the foreseeable future. These forward-looking statements are based on management's current beliefs and assumptions and on information currently available to management. Given their nature, we cannot assure that any outcome expressed in these forward-looking statements will be realized in whole or in part. We caution that these statements are subject to risks and uncertainties, many of which are outside of our control and could cause future events or results to be materially different from those stated or implied in this document, including, among others, factors relating to: • our substantial dependence on the anticipated amount, timing and accounting of revenue from our products, including from the successful development of new products and approval of additional indications for our existing products, including but not limited to LEQEMBI and SKYCLARYS; • the anticipated amount, timing and accounting of contingent, milestone, royalty and other payments under licensing, collaboration, acquisition or divestiture agreements; tax positions and contingencies; collectability of receivables; pre-approval inventory; cost of sales; research and development costs; compensation and other selling, general and administrative expense; amortization of intangible assets; foreign currency exchange risk; estimated fair value of assets and liabilities; and impairment assessments, including for goodwill balances; • expectations, plans, prospects and the timing of actions relating to product approvals, approvals of additional indications for our existing products, sales, pricing, growth, reimbursement and launch of our marketed and pipeline products all of which is subject to governmental and regulatory oversight, and therefore subject to risks and uncertainties, including but not limited to those related to approvals, unfavorable or delayed reimbursements and coverage determinations, and changes in reimbursement policies or practices of payors and other third parties; • the potential impact of increased product competition in the biopharmaceutical and healthcare industry, as well as any other markets in which we compete, including increased competition from new originator therapies, generics, prodrugs and biosimilars of existing products and products approved under abbreviated regulatory pathways, including generic, prodrugs or biosimilar versions of our marketed products or competing products, including but not limited to, increased competition from TECFIDERA generic entrants and a biosimilar entrant of TYSABRI; • patent terms, patent term extensions, patent office actions and expected availability and periods of regulatory exclusivities, as well as our ability to adequately enforce existing patents; Table of Contents • our ability to effectively implement our corporate strategy which includes significant investment in product and pipeline candidates, including but not limited to felzartamab, litifilimab and salanersen; • the successful execution of our strategic and growth initiatives, including acquisitions, and our ability to realize the anticipated benefits from our acquisitions of Reata, HI-Bio and Alcyone, including future performance of the SKYCLARYS product, further development of the felzartamab product and future development of drug delivery solutions; • the drivers for growing our business, including our plans and intention to commit resources relating to discovery, research and development programs and business development opportunities, including collaboration agreements, as well as the potential benefits and results of, and the anticipated completion of, certain business development transactions, reorganizations and cost-reduction measures, including our Fit for Growth program; • the expectations, development plans and anticipated timelines, including costs and timing of potential clinical trials, regulatory filing approvals and/or discontinuation, of our products, drug candidates and pipeline programs, including collaborations with third parties including but not limited to Eisai and Supernus, as well as the potential therapeutic scope of the development and commercialization of our and our collaborators’ products; • the impacts of disruptions, turnover or changes in strategy, priorities or capabilities at our collaborators resulting from, for example, a change in control, and the related impacts on the commercialization or manufacturing of our shared products; • the timing, outcome and impact of administrative, regulatory, legal and other proceedings, including those related to our patents and other proprietary and intellectual property rights, tax audits, assessments and settlements, pricing matters, sales and promotional practices, product liability, investigations and other matters; • our ability to commercialize biosimilars, which is subject to risks such as our reliance on third parties, competitive challenges, regulatory compliance, adequate supply, intellectual property and regulatory challenges and failure to gain market and patient acceptance; • our ability to finance our present and future operations and business initiatives and obtain funding for such activities on favorable terms; • our ability to attract, retain and motivate qualified individuals for management and other employee positions in a highly competitive environment, including potential difficulty in retaining talent following acquisitions or following the discontinuation or underperformance of one or more marketed, preclinical or clinical programs; • adverse safety events involving our marketed or pipeline products, generic, prodrugs or biosimilar versions of our marketed products or any other products from the same class as one of our products; • the current and potential impacts of geopolitical tensions, acts of war and other large-scale crises, including impacts to our operations, sales and the possible disruptions or delay in our plans to conduct clinical trial activities in areas of geopolitical tension, including tensions between the U.S., and China and other countries, regions affected by Russia's invasion of Ukraine and the military conflict in the Middle East; • the impact of new laws, regulatory actions, judicial decisions, accounting standards and tariffs or trade restrictions, including any newly imposed U.S. tariffs and any responsive non-U.S. tariffs applicable to our products or operations, as well as the potential global macroeconomic effect of tariffs or trade restrictions; • the direct and indirect impact of global health outbreaks or adverse weather events on our business and operations, including sales, expense, reserves and allowances, the supply chain, manufacturing, research and development costs, clinical trials and employees; • our use of information technology systems and data and the potential impacts of any breakdowns, interruptions, invasions, corruptions, data breaches, destructions and/or other cybersecurity incidents of such systems or those of our business partners; • our incorporation of technologies using AI into some of our processes; • the potential impact of healthcare reform in the U.S., including the IRA (or other legislative or executive acts that may modify or replace the IRA, such as the OBBBA) and the impact of the IRA Medicare Part D redesign, and measures being taken worldwide designed to reduce healthcare costs and limit the overall level of Table of Contents government expenditures, including the impact of pricing actions and reduced reimbursement for our products, as well as the potential impact of legislative and regulatory changes and priorities, including actions related to MFN drug pricing; • our manufacturing capacity, including our ability to effectively manufacture biosimilars, reliance on third-party contract manufacturing organizations, plans and timing relating to changes in our manufacturing capabilities, our ability to adequately address global bulk supply risks, our ability to fully utilize our manufacturing facilities, including our Solothurn and RTP facilities; • the impact of the continued uncertainty of the credit and economic conditions in certain countries and our ability to collect accounts receivable in such countries; • the impact of the increased volatility in the financial markets on our ability to obtain financing; • lease commitments, purchase obligations and the timing and satisfaction of other contractual obligations; and • changes in our effective tax rate and obligations in various jurisdictions in which we are subject to taxation. These forward-looking statements involve risks and uncertainties, including those that are described in Item 1A. Risk Factors and Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations included in this report and elsewhere in this report, that could cause actual results to differ materially from those reflected in such statements. The factors identified above should not be construed as an exhaustive list of factors that could affect our future results and should be read in conjunction with the other cautionary statements that are included in this Annual Report on Form 10-K. Because some of these risks and uncertainties cannot be predicted or quantified and some are beyond our control, you should not rely on our forward-looking statements as predictions of future events and you should not place undue reliance on these statements. Moreover, we operate in a very competitive and rapidly changing environment, new risks and uncertainties may emerge from time to time and it is not possible for us to predict all risks nor identify all uncertainties. Forward-looking statements speak only as of the date of this report and are based on information and estimates available to us at this time. Except as required by law, we do not undertake any obligation to publicly update any forward-looking statements, whether as a result of new information, future developments or otherwise. You should read this report with the understanding that our actual future results, performance, events and circumstances might be materially different from what we expect. NOTE REGARDING COMPANY AND PRODUCT REFERENCES References in this report to: • “Biogen,” the “company,” “we,” “us” and “our” refer to Biogen Inc. and its consolidated subsidiaries; and • “RITUXAN” refers to both RITUXAN (the trade name for rituximab in the U.S., Canada and Japan) and MabThera (the trade name for rituximab outside the U.S., Canada and Japan). NOTE REGARDING TRADEMARKS ADUHELM®, AVONEX®, PLEGRIDY®, QALSODY®, RITUXAN®, RITUXAN HYCELA®, SKYCLARYS®, SPINRAZA®, TECFIDERA®, THECAFLEX DRX®, TYSABRI® and VUMERITY® are registered trademarks of Biogen. BENEPALI™, FLIXABI™, FUMADERM™ and IMRALDI™ are trademarks of Biogen. ACTEMRA®, COLUMVI®, ENBREL®, EYLEA®, FAMPYRA™, GAZYVA®, LEQEMBI®, HUMIRA®, LUCENTIS®, LUNSUMIO®, OCREVUS®, REMICADE®, TOFIDENCE®, ZURZUVAE® and other trademarks referenced in this report are the property of their respective owners. Table of Contents DEFINED TERMS 2024 Form 10-K Annual Report on Form 10-K for the year ended December 31, 2024 2020 Share Repurchase Program Board of Directors authorized program to repurchase up to $5.0 billion of our common stock 2024 Omnibus Equity Plan Biogen Inc. 2024 Omnibus Equity Plan 2017 Omnibus Equity Plan Biogen Inc. 2017 Omnibus Equity Plan 2024 ESPP Biogen Inc. 2024 Employee Stock Purchase Plan 2015 ESPP Biogen Inc. 2015 Employee Stock Purchase Plan 2023 Term Loan $1.5 billion term loan credit agreement AAIC Alzheimer's Association International Conference AbbVie AbbVie Inc. Acorda Acorda Therapeutics, Inc. AI Artificial Intelligence Alcyone Alcyone Therapeutics, Inc. Alkermes Alkermes plc ALS Amyotrophic Lateral Sclerosis AMP Average Manufacturer Price AMR Antibody-Mediated Rejection AOCI Accumulated Other Comprehensive Income (Loss) ASO Antisense Oligonucleotide ASU Accounting Standards Update BLA Biologics License Application Blackstone Blackstone Life Sciences CCPA California Consumer Privacy Act CEO Chief Executive Officer CHMP Committee for Medicinal Products for Human Use CISO Chief Information Security Officer CLE Cutaneous Lupus Erythematosus CLL Chronic Lymphocytic Leukemia CMS Centers for Medicare & Medicaid Services CNS Central Nervous System CODM Chief Operating Decision Maker Convergence Convergence Pharmaceuticals Ltd. CRL Complete Response Letter CROs Contract Research Organizations CTAD Clinical Trials on Alzheimer's Disease Dayra Dayra Therapeutics, Inc. Denali Denali Therapeutics Inc. Directors Plan Biogen Inc. 2015 Non-Employee Directors Equity Plan District Court U.S. District Court for the District of Massachusetts DOJ U.S. Department of Justice DPN Diabetic Painful Neuropathy EC European Commission EHS Environment, Health and Safety Eisai Eisai Co., Ltd. EMA European Medicines Agency EPO European Patent Office ERG Employee Resource Group ERM Enterprise Risk Management E.U. European Union FA Friedreich Ataxia FASB Financial Accounting Standards Board FCPA Foreign Corrupt Practices Act FDA U.S. Food and Drug Administration Table of Contents DEFINED TERMS (continued) Fit for Growth Cost saving program initiated in 2023 FSS Federal Supply Schedule GCP Good Clinical Practices GDPR General Data Protection Regulation Genentech Genentech, Inc. GILTI Global Intangible Low-Taxed Income GloBE Global Anti-Base Erosion GMP Good Manufacturing Practices HHS U.S. Department of Health and Human Services HI-Bio Human Immunology Biosciences, Inc. Humana Humana Inc. IgAN Immunoglobulin A Nephropathy IND Investigational New Drug Ionis Ionis Pharmaceuticals Inc. IPR&D In-process Research and Development IRA Inflation Reduction Act of 2022 IT Information Technology IV Intravenous LEQEMBI Collaboration Agreement Amended and Restated Collaboration Agreement entered into by Biogen MA Inc. and Eisai Co., Ltd. on October 22, 2017, as amended on March 13, 2022 LRRK2 Leucine-Rich Repeat Kinase 2 LTI Long-term Incentive MAA Marketing Authorization Application MFN Most-Favored-Nation MHRA Medicines and Healthcare products Regulatory Agency MorphoSys MorphoSys AG MS Multiple Sclerosis MVI Microvascular Inflammation in Kidney Transplant Patients NDA New Drug Application NDS New Drug Submission Neurimmune Neurimmune SubOne AG NIST National Institute of Standards and Technology NMPA National Medical Products Administration OBBBA One Big Beautiful Bill Act ODD Orphan Drug Designation OECD Organization for Economic Co-operation and Development OIE Other (Income) Expense, Net Organon Organon LLC PDUFA Prescription Drug User Fee Act PFAS Per- and Polyfluoroalkyl Substances PHS Public Health Service PMN Primary Membranous Nephropathy Polpharma Polpharma Biologics S.A. PPACA Patient Protection and Affordable Care Act PPD Postpartum Depression PPMS Primary Progressive MS PRV Priority Review Voucher R&D Research and Development Reata Reata Pharmaceuticals, Inc. REMS Risk Evaluation and Mitigation Strategies RMS Relapsing MS RNAi RNA Interference Table of Contents DEFINED TERMS (continued) RRMS Relapsing-Remitting MS RTP Research Triangle Park, North Carolina Sage Sage Therapeutics, Inc. Samsung Bioepis Samsung Bioepis Co., Ltd. Samsung BioLogics Samsung BioLogics Co., Ltd. Sangamo Sangamo Therapeutics, Inc. SEC U.S. Securities and Exchange Commission SG&A Selling, General and Administrative SLE Systemic Lupus Erythematosus SMA Spinal Muscular Atrophy SMN Survival Motor Neuron SOD1 Superoxide Dismutase 1 SPC Supplementary Protection Certificate SSP Supplemental Savings Plan Supernus Supernus Pharmaceuticals, Inc. SWISSMEDIC Swiss Agency for Therapeutic Products TNF Anti-tumor Necrosis Factor Transition Toll Tax A one-time mandatory deemed repatriation tax on accumulated foreign subsidiaries' previously untaxed foreign earnings U.K. United Kingdom U.S. United States U.S. GAAP Accounting Principles Generally Accepted in the U.S. VA U.S. Department of Veterans Affairs Vanqua Vanqua Bio, Inc. VAT Value-added Tax Table of Contents PART I ITEM 1. BUSINESS OVERVIEW Biogen is a global biopharmaceutical company focused on discovering, developing and delivering innovative therapies for people living with serious and complex diseases. We have a broad portfolio of medicines to treat MS, have introduced the first approved treatment for SMA, co-developed treatments to address a defining pathology of Alzheimer’s disease and launched the first approved treatment to target a genetic cause of ALS. We market the first and only drug approved in the U.S., the E.U. and certain international markets for the treatment of FA in adults and adolescents aged 16 years and older. We are focused on advancing our pipeline in neurology, specialized immunology and rare diseases. We support our drug discovery and development efforts through internal research and development programs, external collaborations and acquisitions. Our marketed products include VUMERITY, TYSABRI, TECFIDERA, AVONEX and PLEGRIDY for the treatment of MS; SPINRAZA for the treatment of SMA; SKYCLARYS for the treatment of FA; and QALSODY for the treatment of ALS. We also have collaborations with Eisai on the commercialization of LEQEMBI for the treatment of Alzheimer's disease and Supernus on the commercialization of ZURZUVAE for the treatment of PPD. We have certain business and financial rights with respect to RITUXAN for the treatment of non-Hodgkin's lymphoma, CLL and other conditions; RITUXAN HYCELA for the treatment of non-Hodgkin's lymphoma and CLL; GAZYVA for the treatment of CLL, follicular lymphoma and, following its approval in October 2025, lupus nephritis; OCREVUS for the treatment of PPMS and RMS; LUNSUMIO for the treatment of relapsed or refractory follicular lymphoma; COLUMVI, a bispecific antibody for the treatment of non-Hodgkin's lymphoma; and have the option to add other potential anti-CD20 therapies, pursuant to our collaboration arrangements with Genentech, a wholly owned member of the Roche Group. We commercialize a portfolio of biosimilars of advanced biologics including: BENEPALI, an etanercept biosimilar referencing ENBREL; IMRALDI, an adalimumab biosimilar referencing HUMIRA; and FLIXABI, an infliximab biosimilar referencing REMICADE. For additional information on our collaboration arrangements, please read Note 19, Collaborative and Other Relationships , to our consolidated financial statements included in this report. KEY BUSINESS DEVELOPMENTS The following is a summary of key developments affecting our business since the beginning of 2025. ACQUISITIONS ALCYONE THERAPEUTICS, INC. In November 2025 we completed the acquisition of all of the issued and outstanding shares of Alcyone Therapeutics, Inc., a clinical-stage biotechnology company focused on pediatric care through precision CNS therapeutics and dosing platforms. Alcyone's lead asset is ThecaFlex DRx, an implantable subcutaneous port and catheter device being investigated for the intrathecal delivery of ASOs, including SPINRAZA, which is designed to provide an alternative to repeat lumbar punctures in chronic intrathecal administration of medicines. Total consideration for this transaction, which was recorded in acquired in-process research and development, upfront and milestone expense in our consolidated statements of income for the year ended December 31, 2025, was approximately $85.0 million, comprising a $50.0 million payment made upon closing and a $35.0 million payment that was considered probable as of December 31, 2025, and made upon FDA approval of a supplemental application in January 2026. We may pay additional development and regulatory milestone payments to the former shareholders of Alcyone of up to a total of $75.0 million if approval is received for ThecaFlex DRx administration of SPINRAZA or other additional pipeline products. We accounted for this transaction as an asset acquisition as the value being acquired primarily relates to a single asset. U nder the terms of this acquisition, we will oversee the end-to-end development, manufacturing and commercialization of ThecaFlex DRx . 1 Table of Contents For additional information on our acquisition of Alcyone, please read Note 2, Acquisitions, to our consolidated financial statements included in this report. COLLABORATIVE AND OTHER RELATIONSHIPS DAYRA THERAPEUTICS, INC. COLLABORATION In October 2025 we entered into a research collaboration with Dayra to discover and develop oral macrocyclic peptides for priority targets in immunological conditions. Under the terms of this agreement, both companies will collaborate to identify, validate and optimize oral macrocycle candidates for high-priority immunological targets, with our company advancing the molecules through further development and potential commercialization, including manufacturing. In connection with the closing of this transaction we made an upfront payment of $50.0 million to Dayra, which was recognized in acquired in-process research and development, upfront and milestone expense within our consolidated statements of income for the year ended December 31, 2025. This agreement also provides us with the option to acquire the development candidates from Dayra, subject to additional payments per program. Dayra will also be eligible to receive potential preclinical and clinical development milestone payments per program. For additional information on our research arrangement with Dayra, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. VANQUA BIO, INC. COLLABORATION In October 2025 we entered into a license agreement with Vanqua granting us exclusive worldwide rights to further develop, manufacture and commercialize Vanqua's preclinical oral C5aR1 antagonist compound. In connection with the closing of this transaction we made an upfront payment of $70.0 million to Vanqua, which was recognized in acquired in-process research and development, upfront and milestone expense within our consolidated statements of income for the year ended December 31, 2025. We may pay Vanqua potential development, regulatory or commercial, and sales milestone payments of up to $135.0 million, $295.0 million and $560.0 million, respectively, if all the specified milestones set forth in this collaboration are achieved. In addition, we may pay Vanqua tiered royalties on potential net sales of any licensed product under this collaboration in the mid-single digit to low-double digit percentages. For additional information on our license agreement with Vanqua, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. CITY THERAPEUTICS, INC. COLLABORATION In May 2025 we entered into a strategic research arrangement with City Therapeutics to develop select novel RNAi therapies. Through this arrangement, City Therapeutics will leverage its next-generation RNAi engineering technologies to develop an RNAi trigger molecule (or molecules) combined with our proprietary drug delivery technology. The collaboration will initially focus on a single target that mediates key CNS diseases, utilizing tissue enhanced delivery technologies with the aim of allowing for systemic administration of medicines. We will be responsible for IND-enabling studies and global clinical development along with any regulatory submissions and all activities related to commercialization, including manufacturing. In connection with the closing of this transaction we made an upfront payment of $16.0 million to City Therapeutics, which was recognized in acquired in-process research and development, upfront and milestone expense within our consolidated statements of income for the year ended December 31, 2025 , and invested $30.0 million in exchange for a City Therapeutics convertible note, representing a minority equity interest in City Therapeutics, if converted. This convertible note was recorded as a component of investments and other assets within our consolidated balance sheets as of December 31, 2025. For additional information on our strategic research arrangement with City Therapeutics, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. 2 Table of Contents STOKE THERAPEUTICS, INC. COLLABORATION In February 2025 we entered into a collaboration and license agreement with Stoke to co-develop and commercialize zorevunersen, an investigational ASO that targets the SCN1A gene for the potential treatment of Dravet syndrome, a rare form of genetic epilepsy associated with refractory seizures and neurodevelopmental impairments. Zorevunersen dosed its first patient in August 2025, advancing zorevunersen to a global Phase 3 trial. Under the terms of this agreement, Stoke will continue to lead global development and retain exclusive development and commercialization rights for zorevunersen in the U.S., Canada and Mexico and we will have exclusive rights to commercialize zorevunersen in the rest of the world. In connection with the closing of this transaction we made an upfront payment of $165.0 million to Stoke, which was recognized in acquired in-process research and development, upfront and milestone expense within our consolidated statements of income for the year ended December 31, 2025. We also have an exclusive option to license certain future follow-on ASO products targeting the SCN1A gene in all territories worldwide other than the U.S., Canada and Mexico, in exchange for separate milestone, cost sharing and royalty considerations. For additional information on our collaboration arrangement with Stoke, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. ROYALTY PHARMA FUNDING ARRANGEMENT In February 2025 we entered into a funding agreement with Royalty Pharma under which we received $200.0 million in 2025 and will receive up to $50.0 million in 2026 to co-fund our development costs for the litifilimab program. As there is a substantive transfer of risk to the financial partner for the amount invested, the development funding will be recognized by us as an obligation to perform contractual services. This funding is being recognized as a reduction to research and development expense within our consolidated statements of income, proportionate to the related expense. For the year ended December 31, 2025 , we recorded a reduction to research and development e xpense of $200.0 million within our consolidated statements of income. If the litifilimab clinical trials are successful for the indications based on the applicable clinical trials, upon regulatory approval in the U.S. or certain major markets in the world, Royalty Pharma will be eligible to receive approval-based fixed milestone payments of up to $250.0 million. The milestone payments due upon approval will be recorded as a component of other (income) expense, net within our consolidated statements of income, when incurred. If litifilimab receives regulatory approval, Royalty Pharma will be eligible to receive royalties of a mid-single digit percentage of the applicable net sales. Royalties on net sales will be recorded as cost of sales within our consolidated statements of income. For additional information on our funding arrangement with Royalty Pharma, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. DEVELOPMENTS IN KEY COLLABORATIVE RELATIONSHIPS LEQEMBI (lecanemab) United States Key developments related to LEQEMBI in the U.S. consisted of the following: • In January 2026 the FDA accepted for review the supplemental BLA for LEQEMBI subcutaneous autoinjector, LEQEMBI IQLIK, for weekly starting dose, with a PDUFA action date of May 24, 2026. • In August 2025 the FDA approved the BLA for LEQEMBI subcutaneous autoinjector, LEQEMBI IQLIK, for weekly maintenance dosing. • In January 2025 the FDA approved LEQEMBI monthly IV maintenance dosing for the treatment of early Alzheimer's disease. Rest of World Key developments related to LEQEMBI (lecanemab) in rest of world markets consisted of the following: • In January 2026 the BLA for LEQEMBI subcutaneous autoinjector was accepted for review by the NMPA in China. 3 Table of Contents • In November 2025 Eisai filed an NDA for LEQEMBI in Japan seeking approval for a subcutaneous autoinjector as a new route of administration to Japan's Pharmaceuticals and Medical Devices Agency. • In November 2025 the MHRA in the UK approved LEQEMBI monthly IV maintenance dosing for the treatment of early Alzheimer's disease. • In October 2025 Health Canada issued a Notice of Compliance with Conditions for LEQEMBI for the treatment of adult patients with a clinical diagnosis of mild cognitive impairment or mild dementia due to Alzheimer's disease who are either apolipoprotein E ε4 non-carriers or heterozygotes and who have confirmed amyloid pathology. • In September 2025 the National Medical Products Administration in China approved LEQEMBI monthly IV maintenance dosing for the treatment of early Alzheimer's disease. • In September 2025 the Therapeutic Goods Administration of Australia approved LEQEMBI for adults who are either apolipoprotein E ε4 non-carriers or heterozygous carriers. • In June 2025 we filed a request for arbitration in the International Court of Arbitration of the International Chamber of Commerce seeking adoption of a budget and commercialization plan for the European Territory that allocates commercialization activities to Biogen and Eisai in an equitable fashion taking into account our respective capabilities and provides a meaningful role for each party. • In April 2025 the EC approved LEQEMBI in the E.U. for the treatment of adult patients with a clinical diagnosis of mild cognitive impairment and mild dementia due to Alzheimer's disease who are apolipoprotein E ε4 non-carriers or heterozygotes with confirmed amyloid pathology. ZURZUVAE (zuranolone) • In September 2025 the EC approved ZURZUVAE in the E.U. for the treatment of PPD in adults following childbirth, offering the first and only treatment indicated for PPD in the E.U. • In August 2025 the Medicines and Healthcare products Regulatory Agency in the U.K. granted marketing authorization for ZURZUVAE for moderate to severe PPD in the U.K. OTHER KEY DEVELOPMENTS FELZARTAMAB • In June 2025 we announced the initiation of dosing in the global Phase 3 PREVAIL study. This study will evaluate the efficacy and safety of the investigational drug felzartamab compared to placebo on proteinuria and preservation of kidney function in adults diagnosed with IgAN. In connection with the initiation of this dosing we paid a $30.0 million milestone payment to MorphoSys in July 2025. Additionally, in June 2025 we announced the initiation of dosing in the global Phase 3 PROMINENT study. This study will evaluate the efficacy and safety of the investigational drug felzartamab compared to tacrolimus in adults diagnosed with PMN. • In March 2025 we announced the initiation of dosing in the global Phase 3 TRANSCEND study. This study will evaluate the efficacy and safety of the investigational drug felzartamab compared to placebo in adult kidney transplant recipients diagnosed with AMR. In connection with the initiation of this dosing we paid a $35.0 million milestone payment to MorphoSys in April 2025. SPINRAZA (nusinersen) • In January 2026 the EC granted marketing authorization for a high dose regimen of SPINRAZA in the E.U. for the treatment of 5q SMA, which is the most common form of the disease and represents approximately 95% of all SMA cases. The high dose regimen is comprised of 50 mg/5 mL and 28 mg/5 mL doses and individuals transitioning from the 12 mg dose will receive one 50 mg dose in place of their next 12 mg dose, followed by 28 mg maintenance doses every four months thereafter. • In September 2025 the high dose regimen of SPINRAZA was approved by the Ministry of Health, Labour and Welfare in Japan. • In September 2025 the FDA issued a CRL for the supplemental NDA for a higher dose regimen of nusinersen for the treatment of SMA. The CRL requested an update to the technical information to be included in the Chemistry Manufacturing and Controls module of the supplemental NDA and did not cite any deficiencies in the clinical data of the high dose regimen. We resubmitted the supplemental NDA to the FDA, which has been accepted for review with a PDUFA action date of April 3, 2026. 4 Table of Contents SKYCLARYS (omaveloxolone) • In April 2025 SKYCLARYS was approved by the Medicines and Healthcare products Regulatory Agency in the U.K. and in Brazil. In March 2025 SKYCLARYS was approved by Health Canada. QALSODY (tofersen) • In July 2025 the Medicines and Healthcare products Regulatory Agency in the U.K. approved QALSODY for the treatment of ALS in adults who have a mutation in the SOD1 gene. • In March 2025 Health Canada issued marketing authorization with conditions for QALSODY for the treatment of ALS in adults who have a mutation in the SOD1 gene. The authorization is conditional, pending the results of trials to verify its clinical benefit. BIIB080 • In April 2025 the FDA granted Fast Track designation to BIIB080, an investigational ASO therapy targeting tau for the potential treatment of Alzheimer's disease. CORPORATE MATTERS 2025 SENIOR NOTES On May 12, 2025, we issued senior unsecured notes for an aggregate principal amount of $1.75 billion. In June 2025 we used the net proceeds from the sale of our 2025 Senior Notes to redeem our 4.050% Senior Notes due September 15, 2025, prior to maturity. For additional information relating to our 2025 Senior Notes, please read Note 13, Indebtedness , to our consolidated financial statements included in this report. NEW CORPORATE HEADQUARTERS LEASE In March 2025 we entered into a lease agreement with MIT Investment Management Company and BioMed Realty for the lease of approximately 580,000 square feet of office and research and development space located at 75 Broadway, Cambridge, Massachusetts, which will be used as our new global corporate headquarters, as well as integrating our research and development and technical operations teams alongside our North American commercial organization. As part of a multi-year real estate consolidation plan that is expected to result in a reduction of approximately 40% of our real estate footprint in Massachusetts, this new lease is intended to replace two existing leases, both in Cambridge, Massachusetts, including our current corporate headquarters. We expect the initial lease term of approximately 15.5 years to commence on May 31, 2028. For additional information on our lease agreement, please read Note 12, Leases, to our consolidated financial statements included in this report. MANAGEMENT CHANGES • In March 2025 Robin C. Kramer became Executive Vice President and Chief Financial Officer. • In March 2025 Sean Godbout became Vice President, Chief Accounting Officer and Global Corporate Controller. For additional information on our executive officers, please read the subsection entitled "Information about our Executive Officers" included in this report. PRODUCT AND PIPELINE DEVELOPMENTS NEUROLOGY LEQEMBI (lecanemab ) • In December 2025 we and Eisai announced that LEQEMBI has been included in the "Commercial Insurance Innovative Drug List" recently introduced by the National Healthcare Security Administration of China. The Commercial Insurance Innovative Drug List is based on new policies of the Chinese government to support the development and access of innovative medicines. 5 Table of Contents • In December 2025 Eisai presented Phase 3 clinical data confirming pharmacological effect of LEQEMBI at the 2025 CTAD conference. The findings represent the results from a large-scale clinical study demonstrating, for the first time, that binding of lecanemab to protofibrils can be measured in cerebrospinal fluid, enabling further understanding of how lecanemab slows Alzheimer's disease progression. • In July 2025 Eisai announced the interim results of a two-year real-world study of LEQEMBI in the U.S. at the 2025 AAIC conference. The study was conducted to investigate the actual state of real-world clinical treatment with LEQEMBI at 15 medical centers in the U.S., with a final report scheduled for late in the third quarter of Eisai's fiscal year ending March 31, 2026. In this interim study, 83.6% of patients either remained at the same clinical stage or improved from mild dementia to MCI (stable: 76.9%, improvement: 6.7%). Additionally, at time of interim data cut, 86.7% of patients who had received 40 or more doses over 18 months remained stable or showed clinical improvement (stable: 66.7%, improvement: 20%). RARE DISEASE ZOREVUNERSEN • In December 2025 we and Stoke announced new data that further support the potential of zorevunersen, an investigational ASO, as a disease-modifying medicine for Dravet syndrome, at the 2025 American Epilepsy Society Annual Meeting in Atlanta, Georgia. Long-term results from the ongoing Phase 1/2a and OLE studies demonstrated durable seizure reductions, including increases in seizure-free days, in addition to improvements in cognition, behavior and quality of life in patients treated with zorevunersen on top of care anti-seizure medicines. • In November 2025 we and Stoke announced the publication of final data from the BUTTERFLY study, a prospective, two-year natural history study in people with Dravet syndrome, a severe developmental and epileptic encephalopathy characterized by recurrent seizures and significant and behavioral impairments. The BUTTERFLY study evaluated the impact of Dravet syndrome on adaptive functioning and neurodevelopment over two years in children and adolescents ages 2 to 18 years old. Results showed neurodevelopment plateaued at the developmental age of approximately two years old. Over the two-year study, patients experienced minimal changes in cognitive and behavior, including communication, motor skills and personal skills, compared to typical neurodevelopment expected for children of the same age, and major motor seizure frequency increased by 10.6% over two years. • In September 2025 we and Stoke announced data from Phase 1/2a and open-label extension studies of zorevunersen that support the potential for zorevunersen to be the first disease-modifying medicine for Dravet syndrome at the 36th International Epilepsy Congress in Lisbon, Portugal. The study showed durable reductions in seizures and continuing improvements in cognition and behavior through three years in patients who continued to receive zorevunersen in the OLE studies. The study also showed substantial increase in seizure-free days and continuous improvement in quality of life demonstrated in patients already taking standard of care anti-seizure medicines. • In August 2025 we and Stoke announced the first patient dosed in the Phase 3 EMPEROR study of zorevunersen, a potential disease-modifying treatment for Dravet syndrome. • In July 2025 we and Stoke announced the presentation of data from an analysis that informed the design of the Phase 3 EMPEROR study and evaluated the potential effects of the Phase 3 zorevunersen dosing regimen. The data are complementary to previously reported data from a broader cohort of patients treated with zorevunersen in the Phase 1/2a and OLE studies that showed improvements within the first 9 months and continuing improvements through an additional two years. SPINRAZA (nusinersen) • In June 2025 we announced new data that reinforce the clinical impact of nusinersen across a broad spectrum of individuals affected by SMA. These latest findings from Part C of the DEVOTE trial evaluating a higher dose regimen of nusinersen and the NURTURE trial which evaluated the approved 12 mg regimen of SPINRAZA in clinically presymptomatic SMA was presented at the SMA Research & Clinical Care Meeting hosted by Cure SMA. The study showed improvements observed with higher dose regimen of nusinersen in previously treated patient population. 6 Table of Contents SALANERSEN (BIIB115) • In June 2025 we announced positive interim topline results from the Phase 1b study of salanersen, an ASO being developed for the treatment of SMA. Interim Phase 1b data shows children with SMA previously treated with gene therapy experienced a substantial slowing of neurodegeneration and clinically meaningful improvements in motor function following initiation of salanersen. Our Phase 3 registrational study of salanersen is expected to begin in 2026. SKYCLARYS (OMAVELOXOLONE) • In June 2025 we announced the initiation of dosing in the global Phase 3 BRAVE study of omaveloxolone in children with FA between the ages of two to sixteen. The BRAVE study will evaluate the efficacy, safety, pharmacokinetics and pharmacodynamics of omaveloxolone in approximately 255 children living with FA. QALSODY • In December 2025 the Journal of the American Medical Association Neurology published final results from the completed Phase 3 VALOR study and its OLE study evaluating QALSODY for the treatment of SOD1 ALS with over 3.5 years of follow-up. These results show that early initiation of QALSODY was associated with numerically slower decline in measures of clinical function, breathing and strength, as well as reduction in the risk of death or permanent ventilation. Sustained reductions in neurofilament, a marker of neurodegeneration, further validate the clinical results and demonstrate QALSODY's impact on the underlying biology of SOD1 ALS. DISCONTINUED PROGRAMS AND STUDIES SALE OF TOFIDENCE In March 2025 we completed the sale of our regulatory and commercial rights in the U.S. for TOFIDENCE, a tocilizumab biosimilar referencing ACTEMRA, to Organon. Under the terms of this transaction, we received a payment of approximately $51.0 million in July 2025 a nd recognized a de minimis loss within our consolidated statements of income for the year ended December 31, 2025. For additional information on our sale of TOFIDENCE, please read Note 3, Dispositions , to our consolidated financial statements included in this report. SALE OF BYOOVIZ AND OPUVIZ RIGHTS In October 2025 we completed the sale of our remaining commercial rights to two ophthalmology assets in Europe: BYOOVIZ, a ranibizumab biosimilar referencing LUCENTIS, and OPUVIZ, an aflibercept biosimilar referencing EYLEA. Samsung Bioepis will have full responsibility for commercialization of BYOOVIZ upon the transfer of commercial rights from Biogen back to Samsung Bioepis, which became effective as of January 2026. Under the terms of this transaction, we received a payment of $28.0 million in November 2025 and recognized a minimal gain on disposal within our consolidated statements of income for the year ended December 31, 2025. BIIB143 (cemdomespib) In early 2025 we discontinued further development of BIIB143 (cemdomespib) for the treatment of DPN, as part of our ongoing pipeline prioritization efforts. FELZARTAMAB - LUPUS NEPHRITIS In November 2025 we discontinued the open label Phase 1b study of felzartamab for the treatment of lupus nephritis. 7 Table of Contents MARKETED PRODUCTS The following graph shows our product revenue, revenue from anti-CD20 therapeutic programs and Alzheimer's collaboration revenue for the years ended December 31, 2025, 2024 and 2023. (1) MS includes TECFIDERA, VUMERITY, AVONEX, PLEGRIDY, TYSABRI and FAMPYRA. Effective January 1, 2025, our collaboration and license agreement for FAMPYRA global commercialization rights was terminated. (2) Rare disease includes SPINRAZA, QALSODY, which became commercially available in the E.U. during the second quarter of 2024, and SKYCLARYS which became commercially available in the E.U. during the first quarter of 2024. (3) Biosimilars includes BENEPALI, IMRALDI, FLIXABI, BYOOVIZ and TOFIDENCE. In 2025 we completed the sale of our rights to TOFIDENCE and BYOOVIZ. For additional information on our arrangements with Samsung Bioepis, please read Note 19, Collaborative and Other Relationships , to our consolidated financial statements included in this report. (4) Alzheimer's collaboration revenue consists of our 50.0% share of LEQEMBI product revenue, net and cost of sales, including royalties. (5) Anti-CD20 therapeutic programs include RITUXAN, RITUXAN HYCELA, GAZYVA, OCREVUS and LUNSUMIO. (6) Other includes FUMADERM, ADUHELM and ZURZUVAE. 8 Table of Contents Product sales for TYSABRI and SPINRAZA each accounted for more than 10.0% of our total revenue for the years ended December 31, 2025, 2024 and 2023. For additional financial information about our product and other revenue and geographic areas where we operate, please read Note 5, Revenue and Note 25, Segment Information, to our consolidated financial statements included in this report and Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations included in this report. A discussion of the risks attendant to our operations is set forth in Item 1A. Risk Factors included in this report. NEUROLOGY MULTIPLE SCLEROSIS We develop, manufacture and market a number of products designed to treat patients with MS. MS is a progressive disease in which the body loses the ability to transmit messages along nerve cells, leading to a loss of muscle control, paralysis and, in some cases, death. Patients with active RMS experience an uneven pattern of disease progression characterized by periods of stability that are interrupted by flare-ups of the disease after which the patient may return to a lower baseline of functioning. The MS products we market and our major markets are as follows: Product Indication Collaborator Major Markets RMS RRMS in the E.U. Crohn's disease in the U.S. None U.S. Brazil France Germany Italy U.K. RMS in the U.S. RRMS in the E.U. None U.S. France Germany Spain Switzerland U.K. RMS in the U.S. RRMS in the E.U. None U.S. France Germany Italy Japan Poland RMS None U.S. Canada France Germany Italy Spain RMS in the U.S. RRMS in the E.U. None U.S. France Germany Italy Russia Spain U.K. ALZHEIMER'S DISEASE Alzheimer's disease includes LEQEMBI for the treatment of early Alzheimer's disease. Alzheimer's disease, the most common form of dementia, is a progressive neurological illness that causes a gradual decline in cognitive abilities, usually during a span of seven to ten years. Nearly all brain functions, including memory, movement, language, judgement, behavior and abstract thinking, are eventually affected. In the U.S., Alzheimer's disease is the seventh-leading cause of death, accounting for over 120,000 deaths each year. Alzheimer's disease is characterized by two abnormalities in the brain: amyloid plaques and neurofibrillary tangles. Amyloid plaques, which are found in the tissue between the nerve cells, are unusual clumps of a protein called beta amyloid along with degenerating bits of neurons and other cells. Neurofibrillary tangles are bundles of twisted filaments found within neurons. These tangles are largely made up of a protein called tau. 9 Table of Contents Our Alzheimer's disease products and major markets are as follows: Product Indication Collaborator Major Market Alzheimer's disease Eisai U.S. China Japan South Korea For additional information on our collaboration arrangements with Eisai, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. NEUROPSYCHIATRY Neuropsychiatry includes ZURZUVAE for PPD. PPD symptoms are estimated to affect approximately one in eight women who have given birth in the U.S. According to the Centers for Disease Control and Prevention, mental health conditions are the leading cause of maternal mortality with PPD among the most common complications during and after pregnancy. Product Indication Collaborator Major Markets PPD in adults Supernus U.S. For additional information on our collaboration arrangements with Supernus, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. RARE DISEASE Rare disease includes SPINRAZA for SMA, QALSODY for ALS, which became commercially available in the E.U. during the second quarter of 2024, and SKYCLARYS for FA, which became commercially available in the E.U. during the first quarter of 2024. SMA is characterized by loss of motor neurons in the spinal cord and lower brain stem, resulting in severe and progressive muscular atrophy and weakness. Ultimately, individuals with the most severe type of SMA can become paralyzed and have difficulty performing the basic functions of life, like breathing and swallowing. Due to a deletion or mutations in the SMN1 gene, people with SMA do not produce enough SMN protein, which is critical to the survival of the neurons that control muscles. The severity of SMA correlates with the amount of SMN protein. People with Type 1 SMA, the most severe life-threatening form, produce very little SMN protein and do not achieve the ability to sit without support, and typically do not live beyond two years of age without respiratory support and nutritional interventions. People with Type 2 and Type 3 SMA produce greater amounts of SMN protein and have less severe, but still life-altering, forms of SMA. FA is an inherited, debilitating and degenerative neuromuscular disorder that is typically diagnosed during adolescence and can ultimately lead to premature death. Patients with FA experience progressive loss of coordination, muscle weakness and fatigue, which commonly progresses to motor incapacitation, wheelchair reliance and eventually death. ALS is a rare, progressive and fatal neurodegenerative disease that results in the loss of motor neurons in the brain and the spinal cord that are responsible for controlling voluntary muscle movement. People with ALS experience muscle weakness and atrophy, causing them to lose independence as they steadily lose the ability to move, speak, eat and eventually breathe. Average life expectancy for people with ALS is three to five years from time of symptom onset. Multiple genes have been implicated in ALS. Genetic testing helps determine if a person's ALS is associated with a genetic mutation, even in individuals without a known family history of the disease. SOD1-ALS is a mutation in the SOD1 gene, and this form of ALS is diagnosed in approximately two percent of all ALS cases. 10 Table of Contents Our Rare disease products and major markets are as follows: Product Indication Collaborator Major Markets SMA Ionis U.S. Brazil France Germany Italy Poland FA in adults and adolescents aged 16 years and older None U.S. France Germany Greece Italy Turkey ALS in adults with mutation in SOD1 gene Ionis U.S. China Germany Japan Spain For additional information on our collaboration arrangements with Ionis, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. BIOSIMILARS Biosimilars are a group of biologic medicines that are highly similar to currently available biologic therapies developed by companies known as "originators". We commercialize a portfolio of biosimilars of advanced biologics including: BENEPALI, an etanercept biosimilar referencing ENBREL; IMRALDI, an adalimumab biosimilar referencing HUMIRA; and FLIXABI, an infliximab biosimilar referencing REMICADE. Our current biosimilar products and major markets are as follows: Product Indication Collaborator Major Markets Rheumatoid arthritis Juvenile idiopathic arthritis Psoriatic arthritis Axial spondyloarthritis Plaque psoriasis Paediatric plaque psoriasis Samsung Bioepis France Germany Italy Spain Sweden U.K. Rheumatoid arthritis Juvenile idiopathic arthritis Axial spondyloarthritis Psoriatic arthritis Psoriasis Paediatric plaque psoriasis Hidradenitis suppurativa Adolescent hidradenitis suppurativa Crohn’s disease Paediatric Crohn's disease Ulcerative colitis Uveitis Paediatric Uveitis Samsung Bioepis France Germany Ireland Spain Sweden U.K. Rheumatoid arthritis Crohn’s disease Paediatric Crohn’s disease Ulcerative colitis Paediatric ulcerative colitis Ankylosing spondylitis Psoriatic arthritis Psoriasis Samsung Bioepis Austria Germany Italy Norway Spain U.K. For additional information on our collaboration arrangements with Samsung Bioepis, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. 11 Table of Contents GENENTECH RELATIONSHIPS We have agreements with Genentech that entitle us to certain business and financial rights with respect to RITUXAN, RITUXAN HYCELA, GAZYVA, OCREVUS, LUNSUMIO and COLUMVI, as well as the option to add other potential anti-CD20 therapies. Our current anti-CD20 therapeutic programs and major markets are as follows: Product Indication Major Markets Non-Hodgkin's lymphoma CLL Rheumatoid arthritis Two forms of ANCA-associated vasculitis Pemphigus vulgaris U.S. Non-Hodgkin's lymphoma CLL U.S. In combination with chlorambucil for previously untreated CLL follicular lymphoma In combination with chemotherapy followed by GAZYVA alone for previously untreated follicular lymphoma For the treatment of adult patients with active lupus nephritis who are receiving standard therapy U.S. RMS PPMS U.S. Relapsed or refractory follicular lymphoma U.S. Relapsed or refractory diffuse large B-cell lymphoma Large B-cell lymphoma arising from follicular lymphoma U.S. For additional information on our collaboration arrangements with Genentech, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. PATIENT SUPPORT AND ACCESS We interact with patients, advocacy organizations and healthcare societies in order to gain insights into unmet needs. The insights gained from these engagements help us support patients with services, programs and applications that are designed to help transform patients' lives. Among other things, we provide customer service and other related programs for our products, such as disease and product specific websites, insurance research services, financial assistance programs and the facilitation of the procurement of our marketed products. We are dedicated to helping patients obtain access to our therapies. Our patient support representatives have access to a comprehensive suite of financial assistance tools. With those tools, we help patients understand their insurance coverage and, if needed, help patients compare insurance options and programs. In the U.S., we have established programs that provide co-pay assistance for qualified commercially insured patients and free product for qualified uninsured or underinsured patients, based on specific eligibility criteria. We believe all healthcare stakeholders have a shared responsibility to ensure patients have equitable access to new, innovative medicines. We regularly review our pricing strategy and prioritize patient access to our therapies. We have a value-based contracting program designed to align the price of our therapies to the value our therapies deliver 12 Table of Contents to patients. We also work with regulators, clinical researchers, ethicists, physicians and patient advocacy groups and communities, among others, to determine how best to address requests for access to our investigational therapies in ways that are consistent with our patient-focused values and compliant with regulatory standards and protocols. In appropriate situations, patients may have access to investigational therapies through clinical trials, early access programs, post-trial access programs or compassionate use based on humanitarian grounds. MARKETING AND DISTRIBUTION SALES FORCE AND MARKETING We promote our marketed products worldwide, including in the U.S., Europe, Asia, the Middle East and Latin America, primarily through our own sales forces and marketing groups. In some countries, particularly in areas where we continue to expand into new geographic areas, we partner with third parties. RITUXAN, RITUXAN HYCELA, GAZYVA, OCREVUS, LUNSUMIO and COLUMVI are marketed by the Roche Group and its sublicensees. We commercialize BENEPALI, IMRALDI and FLIXABI pursuant to our agreement with Samsung Bioepis in certain international markets. We focus our sales and marketing efforts on health care providers in private practice or at major medical centers. We use customary industry practices to market our products and to educate physicians. This includes our sales representatives calling on individual health care providers (in-person and virtually), advertisements, professional symposia, direct mail, digital marketing, point of care marketing, public relations and other methods. DISTRIBUTION ARRANGEMENTS We distribute our products in the U.S. principally through wholesale and specialty distributors of pharmaceutical products and specialty pharmacies. In other countries, the distribution of our products varies from country to country, including through wholesale distributors of pharmaceutical products and third-party distribution partners who are responsible for most marketing and distribution activities. RITUXAN, RITUXAN HYCELA, GAZYVA, OCREVUS, LUNSUMIO and COLUMVI are distributed by the Roche Group and its sublicensees. We distribute BENEPALI, IMRALDI and FLIXABI in certain countries in Europe and have an option to acquire exclusive rights to distribute these products in China. Our product sales to two wholesale distributors each accounted for more than 10.0% of our total revenue for the years ended December 31, 2025, 2024 and 2023, and on a combined basis, accounted for approximately 43.9%, 39.3% and 36.9%, respectively, of our gross product revenue. For additional information, please read Note 5, Revenue , to our consolidated financial statements included in this report. PATENTS AND OTHER PROPRIETARY RIGHTS Patents are important for obtaining and protecting exclusive rights in our products and product candidates. We regularly seek patent protection in the U.S., the E.U., Asia, the Middle East and Latin America for inventions originating from our research and development efforts and those we license or acquire. In addition, we license rights to various patents and patent applications. U.S. patents, as well as most foreign patents, are generally effective for 20 years from the date the earliest application was filed; however, U.S. patents on applications filed before June 8, 1995, may be effective until 17 years from the issue date, if that is later than the 20-year date. In some cases, the patent term may be extended to recapture a portion of the term lost during regulatory review of the claimed therapeutic or, in the case of the U.S., additional patent term may be awarded due to U.S. Patent and Trademark Office delays in prosecuting the application. In the U.S., under the Drug Price Competition and Patent Term Restoration Act of 1984, commonly known as the Hatch-Waxman Act, a patent that covers a drug approved by the FDA may be eligible for patent term extension (for up to 5 years, but not beyond a total of 14 years from the date of product approval) as compensation for patent term lost during the FDA regulatory review process. The duration and extension of the term of foreign patents vary, in accordance with local law. For example, in a number of European countries, SPCs can be granted to a product to compensate in part for delays in obtaining marketing approval. Regulatory exclusivity, which may consist of regulatory data protection and market protection, can also provide meaningful protection for our products. Regulatory data protection provides to the holder of a drug or biologic 13 Table of Contents marketing authorization, for a set period of time, the exclusive use of the proprietary preclinical and clinical data that it created at significant cost and submitted to the applicable regulatory authority to obtain approval of its product. After the period of exclusive use, third parties are permitted to reference such data in abbreviated applications for approval and to market (subject to any applicable market protection) their generic drugs and biosimilars. Market protection provides the holder of a drug or biologic marketing authorization the exclusive right to commercialize its product for a period of time, thereby preventing the commercialization of another product containing the same active ingredient(s) during that period. Although the World Trade Organization's agreement on trade-related aspects of intellectual property rights requires signatory countries to provide regulatory exclusivity to innovative pharmaceutical products, implementation and enforcement varies widely from country to country. We also rely upon other forms of unpatented confidential information to remain competitive. We protect such information principally through refraining from public disclosure and utilizing confidentiality agreements with our employees, consultants, outside scientific collaborators, scientists whose research we sponsor and other advisers. In the case of our employees, these agreements also provide, in compliance with relevant law, that inventions and other intellectual property conceived by such employees during their employment are our exclusive property. Our trademarks are important to us and are generally covered by trademark applications or registrations in the U.S. Patent and Trademark Office and the patent or trademark offices of other countries. We also use trademarks licensed from third parties. Trademark protection varies in accordance with local law, and continues in some countries as long as the trademark is used and in other countries as long as the trademark is registered. Trademark registrations generally are for fixed but renewable terms. OUR PATENT PORTFOLIO The following table describes certain patents in the U.S. and Europe that we currently consider of primary importance to our marketed products, including the territory, patent number, general subject matter and expected expiration dates. Except as otherwise noted, the expected expiration dates include any granted patent term extensions and issued SPCs. In some instances, there may be additional later-expiring patents relating to our products directed to, among other things, particular forms or compositions, methods of manufacturing or use of the drug in the treatment of particular diseases or conditions. We also continue to pursue additional patents and patent term extensions in the U.S. and other territories covering various aspects of our products that may, if issued, extend exclusivity beyond the expiration of the patents listed in the table. 14 Table of Contents Product Territory Patent No. General Subject Matter Patent Expiration (1) PLEGRIDY U.S. 8,017,733 Polymer conjugates of interferon beta-1a 2027 Europe 1,476,181 Polymer conjugates of interferon-beta-1a and uses thereof 2023 (2) TYSABRI U.S. 8,124,350 Methods of treatment 2027 U.S. 8,871,449 Methods of treatment 2026 U.S. 9,316,641 Safety-related assay 2032 U.S. 9,493,567 Methods of treatment 2027 U.S. 9,709,575 Methods of treatment 2026 U.S. 10,119,976 Methods of evaluating patient risk 2034 U.S. 10,233,245 Methods of treatment 2027 U.S. 10,444,234 Safety-related assay 2031 U.S. 10,677,803 Methods of treatment 2034 U.S. 10,705,095 Methods of treatment 2026 U.S. 11,280,794 Methods of treatment 2034 U.S. 11,287,423 Safety-related assay 2031 U.S. 11,292,845 Methods of treatment 2027 U.S. 12,066,442 Methods of treatment 2032 Europe 1,872,136 Method of treatment 2026 Europe 2,170,390 Formulation 2028 Europe 2,645,106 Method of treatment 2026 Europe 3,264,094 Method of treatment 2026 Europe 3,339,865 Safety-related assay 2031 Europe 3,575,792 Safety-related assay 2032 Europe 4,152,004 Safety-related assay 2031 VUMERITY U.S. 8,669,281 Compounds and pharmaceutical compositions 2033 U.S. 9,090,558 Methods of treatment 2033 U.S. 10,080,733 Crystalline forms, pharmaceutical compositions and methods of treatment 2033 Europe 2,970,101 Crystalline forms, pharmaceutical compositions and methods of treatment Prodrugs of fumarates and their use in treating various diseases 2034 Europe 3,253,377 Formulation 2035 SPINRAZA U.S. 7,838,657 SMA treatment via targeting of SMN2 splice site inhibitory sequences 2027 U.S. 8,361,977 Compositions and methods for modulation of SMN2 splicing 2030 U.S. 8,980,853 Compositions and methods for modulation of SMN2 splicing 2030 U.S. 9,717,750 Compositions and methods for modulation of SMN2 splicing 2030 U.S. 9,926,559 Compositions and methods for modulation of SMN2 splicing 2034 U.S. 10,436,802 Methods for Treating Spinal Muscular Atrophy 2035 U.S. 12,013,403 Methods for Treating Spinal Muscular Atrophy 2036 Europe 1,910,395 Compositions and methods for modulation of SMN2 splicing 2026 (3) Europe 2,548,560 Compositions and methods for modulation of SMN2 splicing 2026 (4) Europe 3,305,302 Compositions and methods for modulation of SMN2 splicing 2030 Europe 3,308,788 Compositions and methods for modulation of SMN2 splicing 2026 Europe 3,449,926 Compositions and methods for modulation of SMN2 splicing 2030 (6) Europe 3,999,643 Methods of Treating or Preventing Spinal Muscular Atrophy 2040 LEQEMBI U.S. 8,025,878 Protofibril selective antibodies and the use thereof 2027 (1)(5) Europe 2,004,688 Improved protofibril selective antibodies and the use thereof 2027 (1)(9) 15 Table of Contents Product Territory Patent No. General Subject Matter Patent Expiration (1) QALSODY U.S. 10,385,341 Compositions for modulating SOD-1 expression 2035 (1)(5) U.S. 10,669,546 Compositions for modulating SOD-1 expression 2035 U.S. 10,968,453 Compositions for modulating SOD-1 expression 2035 Europe 3,126,499 Compositions for modulating SOD-1 expression 2035 (1)(8) Europe 3,757,214 Compositions for modulating SOD-1 expression 2035 ZURZUVAE U.S. 9,512,165 19-nor C3, 3-disubstituted C21-N-pyrazolyl steroids and methods of use thereof 2034 (5) U.S. 10,172,871 19-nor C3, 3-disubstituted C21-N-pyrazolyl steroids and methods of use thereof 2034 (5) U.S. 10,342,810 19-nor C3, 3-disubstituted C21-N-pyrazolyl steroids and methods of use thereof 2034 (5) U.S. 11,236,121 Crystalline 19-nor C3, 3-disubstituted C21-N-pyrazolyl steroid 2034 (5) Europe 2,986,623 19-nor C3, 3-disubstituted c21-N-pyrazolyl steroids and methods of use thereof 2034 Europe 3,498,725 19-nor C3, 3-disubstituted C21-N-pyrazolyl steroid for use in therapy 2034 Europe 3,909,966 19-nor C3, 3-disubstituted C21-N-pyrazolyl steroid for use in therapy 2034 Europe 2,766,380 3.3 disubstituted 10-nore pregnane compounds, compositions and uses thereof 2032 SKYCLARYS U.S. 8,124,799 Antioxidant Inflammation Modulators: Oleanolic Acid Derivatives with Amino and other Modifications at C-17 (Composition) 2029 (5) U.S. 8,440,854 Antioxidant Inflammation Modulators: Oleanolic Acid Derivatives with Amino and other Modifications at C-17 (Composition) 2029 (5) U.S. 8,993,640 2,2-Difluoropropionamide Derivatives of Bardoxolone Methyl, Polymorphic Forms and Methods of Use Thereof (Composition) 2033 (5) U.S. 9,670,147 Antioxidant Inflammation Modulators: Oleanolic Acid Derivatives with Amino and other Modifications at C-17 (Composition) 2029 (5) U.S. 9,701,709 2,2-Difluoropropionamide Derivatives of Bardoxolone Methyl, Polymorphic Forms and Methods of Use Thereof (Composition) 2033 (5) U.S. 11,091,430 Antioxidant Inflammation Modulators: Oleanolic Acid Derivatives with Amino and other Modifications at C-17 (Method of Use) 2029 (5) U.S. 11,919,838 Antioxidant Inflammation Modulators: Oleanolic Acid Derivatives with Amino and other Modifications at C-17 (Method of Use) 2029 (5) Europe 2,276,493 Antioxidant Inflammation Modulators: Oleanolic Acid Derivatives with Amino and other Modifications at C-17 (Composition) 2029 Europe 2,841,445 2,2-Difluoropropionamide Derivatives of Bardoxolone Methyl, Polymorphic Forms and Methods of Use Thereof (Composition) 2033 (7) Europe 3,444,261 2,2-Difluoropropionamide Derivatives of Bardoxolone Methyl, Polymorphic Forms and Methods of Use Thereof (Method of Use) 2033 Footnotes follow on next page. 16 Table of Contents (1) I n addition to patent protection, certain of our products are entitled to regulatory exclusivity in the U.S. and the E.U. expected until the dates set forth below: Product Territory Expected Expiration PLEGRIDY U.S. 2026 SPINRAZA E.U. 2029 LEQEMBI U.S. 2035 LEQEMBI E.U. 2035 QALSODY U.S. 2030 QALSODY E.U. 2034 ZURZUVAE U.S. 2028 ZURZUVAE E.U. 2035 SKYCLARYS U.S. 2030 SKYCLARYS E.U. 2034 (2) This patent is subject to granted SPCs in certain European countries, which extended the patent term in those countries to 2028. (3) This patent is subject to granted SPCs in certain European countries, which extended the patent term in those countries to 2031. (4) This patent is subject to granted SPCs in certain European countries, which extended the patent term in those countries to 2031. (5) A patent with this subject matter may be entitled to patent term extension in the U.S. (6) This patent is subject to granted SPCs in certain European countries, which extended the patent term in those countries to 2032. (7) This patent is subject to granted SPCs in certain European countries, which extended the patent term in those countries to 2038. (8) This patent is subject to granted SPCs in certain European countries, which extended the patent term in those countries to 2039. (9) SPC applications based on this patent have been filed in certain European countries, which if granted would extend the patent term in those countries to 2032. The existence of patents does not guarantee our right to practice the patented technology or commercialize the patented product. Patents relating to pharmaceutical, biopharmaceutical and biotechnology products, compounds and processes, such as those that cover our existing products, compounds and processes and those that we will likely file in the future, do not always provide complete or adequate protection. Litigation, interferences, oppositions, inter partes reviews, administrative challenges or other similar types of proceedings are, have been and may in the future be necessary in some instances to determine the validity and scope of certain of our patents, regulatory exclusivities or other proprietary rights, and in other instances to determine the validity, scope or non-infringement of certain patent rights claimed by third parties to be pertinent to the manufacture, use or sale of our products. We also face challenges to our patents, regulatory exclusivities or other proprietary rights covering our products by third parties, such as manufacturers of generics, biosimilars, prodrugs and products approved under abbreviated regulatory pathways. A discussion of certain risks and uncertainties that may affect our patent position, regulatory exclusivities or other proprietary rights is set forth in Item 1A. Risk Factors included in this report, and the discussion of legal proceedings related to certain patents described above is set forth in Note 21, Litigation, to our consolidated financial statements included in this report. 17 Table of Contents COMPETITION Competition in the biopharmaceutical industry and the markets in which we operate is intense. There are many companies, including biotechnology and pharmaceutical companies, engaged in developing products for the indications our approved products are approved to treat and the therapeutic areas we are targeting with our research and development activities. Some of our competitors may have substantially greater financial, marketing, research and development and other resources than we do. We believe that competition and leadership in the industry is based on scientific, managerial and technological excellence and innovation, as well as establishing patent and other proprietary positions through research and development. The achievement of a leadership position also depends largely upon our ability to maximize the approval, acceptance and use of our product candidates and the availability of adequate financial resources to fund facilities, equipment, personnel, clinical testing, manufacturing and marketing. Another key aspect of remaining competitive in the industry is recruiting and retaining leading scientists and technicians to conduct our research activities and advance our development programs, including with the regulatory and commercial expertise to effectively advance and market our products. Competition among products approved for sale may be based, among other things, on patent position, product efficacy, safety, patient convenience, delivery devices, reliability, availability, reimbursement and price. In addition, early entry of a new pharmaceutical product into the market may have important advantages in gaining product acceptance and market share. Accordingly, the relative speed with which we can develop products, complete the testing and approval process and supply commercial quantities of products will have a significant impact on our competitive position. The introduction of new products or technologies, including the development of new processes or technologies by competitors or new information about existing products or technologies, results in increased competition for our marketed products and pricing pressure on our marketed products. The development of new or improved treatment options could eliminate the use of our products or may limit the utility and application of ongoing clinical trials for our product candidates. Similarly, developments of new standards of care practices, treatment options or cures for the diseases our products treat could have similar impacts. We believe our long-term competitive position depends upon our success in discovering and developing innovative, cost-effective products that serve unmet medical needs, along with our ability to manufacture products efficiently and to launch and market them effectively in a highly competitive environment. Additional information about the competition that our marketed products face is set forth below and in Item 1A. Risk Factors included in this report. GENERIC AND BIOSIMILARS COMPETITION Certain of our products already face, or may face in the future, competition from the introduction of new originator therapies, generics, prodrugs and biosimilars of existing products and products approved under abbreviated regulatory pathways. Such products are likely to be sold at substantially lower prices than branded products. Accordingly, the introduction of such products as well as other lower-priced competing products may significantly reduce both the price that we are able to charge for our products and the volume of products we sell, which will negatively impact our revenue. In some jurisdictions a decrease in reimbursed price is mandated by law. In addition, in some markets, when a generic or biosimilar version of one of our products is commercialized, it may be automatically substituted for our product and significantly reduce our revenue in a short period of time. TECFIDERA Multiple TECFIDERA generic entrants are now in North America, Brazil and certain European countries and have deeply discounted prices compared to TECFIDERA. The generic competition for TECFIDERA has significantly reduced our TECFIDERA revenue and we expect that TECFIDERA revenue will continue to decline. In November 2025 the Technical Boards of Appeal of the European Patent Office revoked our EP 2 653 873 patent related to TECFIDERA, after which we stopped enforcing this patent and its national counterparts. RITUXAN B i osimilar products referencing RITUXAN are available in the U.S and are being offered at lower prices. This competition has had a significant adverse impact on the pre-tax profits of our collaboration arrangements with 18 Table of Contents Genentech, as the sales of RITUXAN have decreased substantially compared to prior periods and we expect sales to continue to decrease. TYSABRI A biosimilar entrant of TYSABRI was approved in the U.S. and the E.U. in 2023. We expect that future sales of TYSABRI will continue to be adversely affected by the entrance of this biosimilar worldwide. NEUROLOGY MULTIPLE SCLEROSIS Competition in the MS market is intense. Along with us, a number of companies are working to develop additional treatments for MS that may in the future compete with our MS products. Our MS products may be adversely affected if competitors continue to gain market share, or if other MS products that we or our competitors are developing are commercialized. ALZHEIMER'S DISEASE The market for the treatment of Alzheimer's disease is developing and could be subject to rapid change in the future. Most current treatments are symptomatic or intended to improve quality of life. We and our collaboration partner Eisai co-commercialize LEQEMBI, an anti-amyloid antibody for the treatment of Alzheimer's disease. Along with us, several companies are working to develop additional treatments. A competing product, KISUNLA, a treatment for early symptomatic Alzheimer's disease that was developed by Eli Lilly and Company, was approved in the U.S. in 2024 and in the E.U. in 2025. We are aware of other products now in development that, if approved, may also compete with LEQEMBI. RARE DISEASE SPINAL MUSCULAR ATROPHY We face competition from an oral product EVRYSDI (risdiplam) and a gene therapy product ZOLGENSMA (onasemnogene abeparvovec-xioi). We expect that we will experience competition from both products in additional jurisdictions and new formulations of those products, which may adversely affect our sales of SPINRAZA. 19 Table of Contents RESEARCH AND DEVELOPMENT PROGRAMS A commitment to research and development is fundamental to our mission. Our research efforts are focused on better understanding the underlying biology of diseases so we can discover and deliver treatments that have the potential to make a real difference in the lives of patients with high unmet medical needs. By applying our expertise in biologics and our capabilities in small molecule, antisense and other technologies, we target specific medical needs where we believe new or better treatments are needed. We intend to continue committing significant resources to targeted research and development opportunities where there is a significant unmet need and where a drug candidate has the potential to be highly differentiated. As part of our ongoing research and development efforts, we have devoted significant resources to conducting clinical studies to advance the development of new pharmaceutical products and technologies and to explore the utility of our existing products in treating disorders beyond those currently approved in their labels. For additional information on our research and development expense included in our consolidated statements of income, please read Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations included in this report. The table below highlights our current research and development programs that are in clinical trials and the current phase of such programs. Drug development involves a high degree of risk and investment, and the status, timing and scope of our development programs are subject to change. Important factors that could adversely affect our drug development efforts are discussed in Item 1A. Risk Factors included in this report. Neurology Lecanemab (Aβ mAb) (1) - Preclinical Alzheimer's Phase 3 BIIB080 (tau ASO) (1) - Alzheimer's Phase 2 BIIB122 (LRRK2 inhibitor) (1) - Parkinson's Phase 2 BIIB091 (peripheral BTK inhibitor) - MS Phase 2 Immunology Dapirolizumab pegol (anti-CD40L) (1) - SLE Phase 3 Litifilimab (anti-BDCA2) - SLE Phase 3 Litifilimab (anti-BDCA2) - CLE Phase 3 BIIB142 (IRAK4 degrader) (1) Phase 1 BIIB145 (BTK degrader) (1) Phase 1 Rare Disease Felzartamab (anti-CD38 mAb) - AMR Phase 3 Felzartamab (anti-CD38 mAb) - IgAN Phase 3 Felzartamab (anti-CD38 mAb) - PMN Phase 3 Felzartamab (anti-CD38 mAb) - MVI Phase 2 Omaveloxolone (Nrf2 activator) - Pediatric FA Phase 3 Salanersen BIIB115 (SMN ASO) (1) - SMA Phase 3 Zorevunersen (SCN1A ASO) (1) - Dravet syndrome Phase 3 (1) Collaboration program For information about certain of our agreements with collaborators and other third parties, please read the subsection entitled Business Relationships below and Note 2, Acquisitions and Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in this report. BUSINESS RELATIONSHIPS As part of our business strategy, we establish business relationships, including entering into licenses, joint ventures and collaborative arrangements with other companies, universities and medical research institutions, to assist in the clinical development and/or commercialization of certain of our products and product candidates and to provide support for our research programs. We also evaluate opportunities for acquiring products or rights to products and technologies that are complementary to our business from other companies, universities and medical research institutions. Below is a brief description of certain business relationships and collaborations that expand our pipeline and provide us with certain rights to existing and potential new products and technologies. For additional information on certain 20 Table of Contents of these relationships, including their ongoing financial and accounting impact on our business, please read Note 19, Collaborative and Other Relationships , to our consolidated financial statements included in this report. EISAI We have a collaboration agreement with Eisai to jointly develop and commercialize LEQEMBI (lecanemab), an anti-amyloid antibody for the treatment of Alzheimer's disease. Subject to the limitations in the LEQEMBI Collaboration Agreement, Eisai has final decision-making authority on all matters relating to the collaboration and serves as the lead of LEQEMBI development and regulatory submissions globally. We co-commercialize and co-promote LEQEMBI with Eisai. Our Collaboration Agreement provides that each commercialization plan shall allocate the responsibilities for the activities under the plan in an equitable fashion taking into account Biogen's and Eisai's respective capabilities and provides a meaningful role for each party. All costs, including research, development, sales and marketing expense, are shared equally between us and Eisai. We also share profits and losses equally. We currently have a supply agreement with Eisai to manufacture LEQEMBI drug substance and drug product through the end of 2031. SUPERNUS (PREVIOUSLY SAGE) We have a global collaboration and license agreement with Supernus to jointly develop and commercialize ZURZUVAE (zuranolone) for the treatment of PPD. Under this collaboration, both companies will share equal responsibility and costs for development as well as profits and losses for commercialization in the U.S. Outside of the U.S., we are responsible for development and commercialization, excluding Japan, Taiwan and South Korea. GENENTECH We have agreements with Genentech that entitle us to certain business and financial rights with respect to RITUXAN, RITUXAN HYCELA, GAZYVA, OCREVUS, LUNSUMIO and COLUMVI, as well as the option to add other potential anti-CD20 therapies. UCB We have a collaboration agreement with UCB to jointly develop and commercialize dapirolizumab pegol, an anti-CD40L pegylated Fab, for the potential treatment of SLE and other future agreed indications. All costs incurred for agreed indications, including research, development, sales and marketing expense, are shared equally between us and UCB. If marketing approval is obtained, both companies will jointly commercialize dapirolizumab pegol and share profits and losses equally. IONIS We have several exclusive, worldwide option and collaboration agreements with Ionis to develop and commercialize antisense therapeutics, including SPINRAZA for the treatment of SMA and QALSODY for the treatment of ALS with SOD1 mutations, as well as other research programs for a broad range of neurological diseases. Under these agreements, we have the option to license therapies arising out of these collaborations and will be responsible for their development and commercialization. Ionis may receive potential milestones and royalties on net sales if we successfully develop the product candidate after option exercise. We have worldwide, exclusive, royalty-bearing licenses to develop and commercialize salanersen (BIIB115), an investigational ASO in development for SMA and BIIB080 (tau ASO) for the potential treatment of Alzheimer's disease. DENALI We have a collaboration and license agreement with Denali to co-develop and co-commercialize BIIB122, a small molecule inhibitor of LRRK2 for Parkinson's disease (LRRK2 Collaboration). Under the LRRK2 Collaboration, both companies share responsibility and costs for global development based on specified percentages as well as profits and losses for commercialization in the U.S. and China. Outside the U.S. and China we are responsible for commercialization and may pay Denali potential tiered royalties. STOKE We have a collaboration and license agreement with Stoke to co-develop and commercialize zorevunersen, an investigational ASO that targets the SCN1A gene for the potential treatment of Dravet syndrome, a rare form of genetic epilepsy associated with refractory seizures and neurodevelopmental impairments. Under this agreement, Stoke will continue to lead global development and retain exclusive development and commercialization rights for 21 Table of Contents zorevunersen in the U.S., Canada and Mexico and we will have exclusive rights to commercialize zorevunersen in the rest of the world. SAMSUNG BIOEPIS We have an agreement with Samsung Bioepis to commercialize three anti-TNF biosimilar product candidates in certain countries in Europe. Under this agreement, we are commercializing BENEPALI, an etanercept biosimilar referencing ENBREL, IMRALDI, an adalimumab biosimilar referencing HUMIRA, and FLIXABI, an infliximab biosimilar referencing REMICADE. In addition to our commercialization agreements with Samsung Bioepis, we license certain of our proprietary technology to Samsung Bioepis in connection with Samsung Bioepis' development, manufacture and commercialization of its biosimilar products. REGULATORY Our current and contemplated activities and the products, technologies and processes that result from such activities are subject to substantial government regulation. REGULATION OF PHARMACEUTICALS PRODUCT APPROVAL AND POST-APPROVAL REGULATION IN THE U.S. APPROVAL PROCESS Before new pharmaceutical products may be sold in the U.S., preclinical studies and clinical trials of the products must be conducted and the results submitted to the FDA for approval. With limited exceptions, the FDA requires companies to register both pre-approval and post-approval clinical trials and disclose clinical trial results in public databases. Failure to register a trial or disclose study results within the required time periods could result in penalties, including civil monetary penalties. Clinical trial programs must establish efficacy, determine an appropriate dose and dosing regimen and define the conditions for safe use. This is a high-risk process that requires stepwise clinical studies in which the candidate product must successfully meet predetermined endpoints. The results of the preclinical and clinical testing of a product are then submitted to the FDA in the form of a BLA or NDA. In response to a BLA or NDA, the FDA may grant marketing approval, request additional information or deny the application if it determines the application does not provide an adequate basis for approval. Product development and receipt of regulatory approval takes a number of years, involves the expenditure of substantial resources and depends on a number of factors, including the severity of the disease in question, the availability of suitable alternative treatments, potential safety signals observed in preclinical or clinical tests and the risks and benefits of the product as demonstrated in clinical trials. The FDA has substantial discretion in the product approval process, and it is impossible to predict with any certainty whether and when the FDA will grant marketing approval. The agency may require the sponsor of a BLA or NDA to conduct additional clinical studies or to provide other scientific or technical information about the product, and these additional requirements may lead to unanticipated delays and/or expenses. Furthermore, even if a product is approved, the approval may be subject to limitations based on the FDA's interpretation of the existing preclinical and/or clinical data. The FDA has developed four distinct approaches intended to facilitate the development and expedite the regulatory review of therapeutically important drugs, especially when the drugs are the first available treatment or have advantages over existing treatments: accelerated approval, fast track, breakthrough therapy and priority review. • Accelerated Approval : The FDA may grant “accelerated approval” to products that treat serious or life-threatening illnesses and that provide meaningful therapeutic benefits to patients over existing treatments. Under this pathway, the FDA may approve a product based on surrogate endpoints or clinical endpoints other than survival or irreversible morbidity. When approval is based on surrogate endpoints or clinical endpoints other than survival or morbidity, the sponsor will be required to provide the FDA with confirmatory data post-approval to verify and describe clinical benefit. Under the FDA's accelerated approval regulations, if the FDA concludes that a drug that has been shown to be effective can be safely used only if distribution or use is restricted, it may require certain post-marketing restrictions to assure safe use. In addition, for products approved under accelerated approval, sponsors may be required to submit all copies of their promotional materials, including advertisements, to the FDA at least 30 days prior to initial dissemination. The FDA may withdraw approval if, for instance, post-marketing studies fail to verify clinical benefit, it becomes clear that 22 Table of Contents restrictions on the distribution of the product are inadequate to ensure its safe use or if a sponsor fails to comply with the conditions of the accelerated approval. • Fast Track : The FDA may grant "fast track" status to products that treat a serious condition and have data demonstrating the potential to address an unmet medical need or a drug that has been designated as a qualified infectious disease product. • Breakthrough Therapy : The FDA may grant “breakthrough therapy” status to drugs designed to treat, alone or in combination with another drug or drugs, a serious or life-threatening disease or condition and for which preliminary clinical evidence suggests a substantial improvement over existing therapies based on a clinically significant endpoint. Breakthrough therapy status entitles the sponsor to earlier and more frequent meetings with the FDA regarding the development of nonclinical and clinical data and permits the FDA to offer product development or regulatory advice for the purpose of shortening the time to product approval. Breakthrough therapy status does not guarantee that a product will be eligible for priority review and does not ensure FDA approval. • Priority Review : “Priority review” only applies to applications (original or efficacy supplement) for a drug that treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness of the treatment, diagnosis or prevention of a serious condition. Priority review may also be granted for any supplement that proposes a labeling change due to studies completed in response to a written request from the FDA for pediatric studies, for an application for a drug that has been designated as a qualified infectious disease product or for any application or supplement for a drug submitted with a PRV. As part of our acquisition of Reata in September 2023 we obtained a rare pediatric disease PRV in connection with the approval of SKYCLARYS, which was approved by the FDA in February 2023. POST-MARKETING STUDIES Regardless of the approval pathway employed, the FDA may require a sponsor to conduct additional post-marketing studies as a condition of approval to provide data on safety and effectiveness. If a sponsor fails to conduct the required studies, the FDA may withdraw its approval. In addition, if the FDA concludes that a drug that has been shown to be effective can be safely used only if distribution or use is restricted, it can mandate post-marketing restrictions to assure safe use. In such a case, the sponsor may be required to establish rigorous systems to assure use of the product under safe conditions. These systems are usually referred to as REMS. The FDA can impose financial penalties for failing to comply with certain post-marketing commitments, including REMS. In addition, any changes to an approved REMS must be reviewed and approved by the FDA prior to implementation. ADVERSE EVENT REPORTING We monitor information on side effects and adverse events reported during clinical studies and after marketing approval and report such information and events to regulatory agencies. Non-compliance with the FDA's safety reporting requirements may result in civil or criminal penalties. Side effects or adverse events that are reported during clinical trials can delay, impede or prevent marketing approval. Based on new safety information that emerges after approval, the FDA can mandate product labeling changes, impose a new REMS or the addition of elements to an existing REMS, require new post-marketing studies (including additional clinical trials) or suspend or withdraw approval of the product. These requirements may affect our ability to maintain marketing approval of our products or require us to make significant expenditures to obtain or maintain such approvals. APPROVAL OF CHANGES TO AN APPROVED PRODUCT If we seek to make certain types of changes to an approved product, such as adding a new indication, making certain manufacturing changes or changing manufacturers or suppliers of certain ingredients or components, the FDA will need to review and approve such changes in advance. In the case of a new indication, we are required to demonstrate with additional clinical data that the product is safe and effective for a use other than what was initially approved. FDA regulatory review may result in denial or modification of the planned changes, or requirements to conduct additional tests or evaluations that can substantially delay or increase the cost of the planned changes. REGULATION OF PRODUCT ADVERTISING AND PROMOTION The FDA regulates all advertising and promotion activities and communications for products under its jurisdiction both before and after approval. Pursuant to FDA guidance, a company can make safety and efficacy claims either in or consistent with the product label. However, physicians may prescribe legally available drugs for uses that are not described in the drug's labeling. Such off-label prescribing is common across medical specialties, and often reflects a physician's belief that the off-label use is the best treatment for patients. The FDA does not regulate the behavior of physicians in their choice of treatments, but FDA regulations do impose stringent restrictions on manufacturers' 23 Table of Contents