Biogen 10-K 2025-12-31

Filed 2026-02-06. 24 sections, 838K characters. Original on sec.gov · Markdown · JSON

What changed since the 2024-12-31 10-KNew, removed and reworded risk factor headings, then every item sentence by sentence.

Cover and table of contents

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

biogenlogo2020a01.jpg

BIOGEN INC.

(Exact name of registrant as specified in its charter)

Delaware33-0112644
(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 ClassTrading Symbol(s)Name of Each Exchange on Which Registered
Common Stock, $0.0005 par valueBIIBTheNasdaq 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 filerxAccelerated 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.

BIOGEN INC.

ANNUAL REPORT ON FORM 10-K

For the Year Ended December 31, 2025

TABLE OF CONTENTS

Page
PART I
Item 1.Business1
Item 1A.Risk Factors39
Item 1B.Unresolved Staff Comments54
Item 1C.Cybersecurity54
Item 2.Properties55
Item 3.Legal Proceedings56
Item 4.Mine Safety Disclosures56
PART II
Item 5.Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities57
Item 6.Reserved58
Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations59
Item 7A.Quantitative and Qualitative Disclosures About Market Risk93
Item 8.Financial Statements and Supplementary Data94
Item 9.Changes in and Disagreements with Accountants on Accounting and Financial Disclosure94
Item 9A.Controls and Procedures94
Item 9B.Other Information95
Item 9C.Disclosure Regarding Foreign Jurisdictions that Prevent Inspections95
PART III
Item 10.Directors, Executive Officers and Corporate Governance96
Item 11.Executive Compensation96
Item 12.Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters96
Item 13.Certain Relationships and Related Transactions, and Director Independence96
Item 14.Principal Accountant Fees and Services96
PART IV
Item 15.Exhibits and Financial Statement Schedules97
Item 16.Form 10-K Summary97
Signatures100
Consolidated Financial StatementsF- 1

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;

  • 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

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.

DEFINED TERMS

2024 Form 10-KAnnual Report on Form 10-K for the year ended December 31, 2024
2020 Share Repurchase ProgramBoard of Directors authorized program to repurchase up to $5.0 billion of our common stock
2024 Omnibus Equity PlanBiogen Inc. 2024 Omnibus Equity Plan
2017 Omnibus Equity PlanBiogen Inc. 2017 Omnibus Equity Plan
2024 ESPPBiogen Inc. 2024 Employee Stock Purchase Plan
2015 ESPPBiogen Inc. 2015 Employee Stock Purchase Plan
2023 Term Loan$1.5 billion term loan credit agreement
AAICAlzheimer's Association International Conference
AbbVieAbbVie Inc.
AcordaAcorda Therapeutics, Inc.
AIArtificial Intelligence
AlcyoneAlcyone Therapeutics, Inc.
AlkermesAlkermes plc
ALSAmyotrophic Lateral Sclerosis
AMPAverage Manufacturer Price
AMRAntibody-Mediated Rejection
AOCIAccumulated Other Comprehensive Income (Loss)
ASOAntisense Oligonucleotide
ASUAccounting Standards Update
BLABiologics License Application
BlackstoneBlackstone Life Sciences
CCPACalifornia Consumer Privacy Act
CEOChief Executive Officer
CHMPCommittee for Medicinal Products for Human Use
CISOChief Information Security Officer
CLECutaneous Lupus Erythematosus
CLLChronic Lymphocytic Leukemia
CMSCenters for Medicare & Medicaid Services
CNSCentral Nervous System
CODMChief Operating Decision Maker
ConvergenceConvergence Pharmaceuticals Ltd.
CRLComplete Response Letter
CROsContract Research Organizations
CTADClinical Trials on Alzheimer's Disease
DayraDayra Therapeutics, Inc.
DenaliDenali Therapeutics Inc.
Directors PlanBiogen Inc. 2015 Non-Employee Directors Equity Plan
District CourtU.S. District Court for the District of Massachusetts
DOJU.S. Department of Justice
DPNDiabetic Painful Neuropathy
ECEuropean Commission
EHSEnvironment, Health and Safety
EisaiEisai Co., Ltd.
EMAEuropean Medicines Agency
EPOEuropean Patent Office
ERGEmployee Resource Group
ERMEnterprise Risk Management
E.U.European Union
FAFriedreich Ataxia
FASBFinancial Accounting Standards Board
FCPAForeign Corrupt Practices Act
FDAU.S. Food and Drug Administration

DEFINED TERMS (continued)

Fit for GrowthCost saving program initiated in 2023
FSSFederal Supply Schedule
GCPGood Clinical Practices
GDPRGeneral Data Protection Regulation
GenentechGenentech, Inc.
GILTIGlobal Intangible Low-Taxed Income
GloBEGlobal Anti-Base Erosion
GMPGood Manufacturing Practices
HHSU.S. Department of Health and Human Services
HI-BioHuman Immunology Biosciences, Inc.
HumanaHumana Inc.
IgANImmunoglobulin A Nephropathy
INDInvestigational New Drug
IonisIonis Pharmaceuticals Inc.
IPR&DIn-process Research and Development
IRAInflation Reduction Act of 2022
ITInformation Technology
IVIntravenous
LEQEMBI Collaboration AgreementAmended and Restated Collaboration Agreement entered into by Biogen MA Inc. and Eisai Co., Ltd. on October 22, 2017, as amended on March 13, 2022
LRRK2Leucine-Rich Repeat Kinase 2
LTILong-term Incentive
MAAMarketing Authorization Application
MFNMost-Favored-Nation
MHRAMedicines and Healthcare products Regulatory Agency
MorphoSysMorphoSys AG
MSMultiple Sclerosis
MVIMicrovascular Inflammation in Kidney Transplant Patients
NDANew Drug Application
NDSNew Drug Submission
NeurimmuneNeurimmune SubOne AG
NISTNational Institute of Standards and Technology
NMPANational Medical Products Administration
OBBBAOne Big Beautiful Bill Act
ODDOrphan Drug Designation
OECDOrganization for Economic Co-operation and Development
OIEOther (Income) Expense, Net
OrganonOrganon LLC
PDUFAPrescription Drug User Fee Act
PFASPer- and Polyfluoroalkyl Substances
PHSPublic Health Service
PMNPrimary Membranous Nephropathy
PolpharmaPolpharma Biologics S.A.
PPACAPatient Protection and Affordable Care Act
PPDPostpartum Depression
PPMSPrimary Progressive MS
PRVPriority Review Voucher
R&DResearch and Development
ReataReata Pharmaceuticals, Inc.
REMSRisk Evaluation and Mitigation Strategies
RMSRelapsing MS
RNAiRNA Interference

DEFINED TERMS (continued)

RRMSRelapsing-Remitting MS
RTPResearch Triangle Park, North Carolina
SageSage Therapeutics, Inc.
Samsung BioepisSamsung Bioepis Co., Ltd.
Samsung BioLogicsSamsung BioLogics Co., Ltd.
SangamoSangamo Therapeutics, Inc.
SECU.S. Securities and Exchange Commission
SG&ASelling, General and Administrative
SLESystemic Lupus Erythematosus
SMASpinal Muscular Atrophy
SMNSurvival Motor Neuron
SOD1Superoxide Dismutase 1
SPCSupplementary Protection Certificate
SSPSupplemental Savings Plan
SupernusSupernus Pharmaceuticals, Inc.
SWISSMEDICSwiss Agency for Therapeutic Products
TNFAnti-tumor Necrosis Factor
Transition Toll TaxA one-time mandatory deemed repatriation tax on accumulated foreign subsidiaries' previously untaxed foreign earnings
U.K.United Kingdom
U.S.United States
U.S. GAAPAccounting Principles Generally Accepted in the U.S.
VAU.S. Department of Veterans Affairs
VanquaVanqua Bio, Inc.
VATValue-added Tax

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. Under the terms of this acquisition, we will oversee the end-to-end development, manufacturing and commercialization of ThecaFlex DRx.

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 consol

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Item 1A. RISK FACTORS

Risks Related to Our Business

We are substantially dependent on revenue from our products.

Our revenue depends upon continued sales of our products as well as the financial rights we have in our anti-CD20 therapeutic programs. A significant portion of our revenue is concentrated on sales of our products in increasingly competitive markets. Any of the following negative developments relating to any of our products or any of our anti-CD20 therapeutic programs may adversely affect our revenue and results of operations or our stock price:

  • the introduction, greater acceptance or more favorable reimbursement of competing products, including new originator therapies, generics, prodrugs and biosimilars of existing products and products approved under abbreviated regulatory pathways;

  • safety or efficacy issues;

  • limitations and additional pressures on product pricing or price increases, including those relating to inflation and those resulting from governmental or regulatory requirements, including those relating to any future potential drug price negotiation under the IRA or other legislative or executive acts; increased competition, including from generic or biosimilar versions of our products; or changes in, or implementation of, reimbursement policies and practices of payors and other third parties;

  • adverse legal, administrative, geopolitical, regulatory or legislative developments; and

  • our ability to maintain a positive reputation among patients, healthcare providers and others, which may be impacted by our pricing and reimbursement decisions.

LEQEMBI is in the early stages of commercial launch in the U.S. and certain international markets and SKYCLARYS is in the early stages of commercial launch in certain European markets. In addition to risks associated with new product launches and the other factors described in these Risk Factors, Biogen’s and Eisai’s ability to successfully commercialize LEQEMBI and our ability to successfully commercialize SKYCLARYS may be adversely affected due to:

  • Eisai’s ability to obtain and maintain adequate reimbursement for LEQEMBI;

  • the effectiveness of Eisai's and Biogen’s commercial strategy for marketing LEQEMBI;

  • requirements such as participation in a registry and the use of imaging or other diagnostics for LEQEMBI;

  • our ability to obtain approval in other markets;

  • the approval and/or greater acceptance of other new products for the same or similar indications;

  • Eisai’s and Biogen’s ability to maintain a positive reputation among patients, healthcare providers and others in the Alzheimer’s disease community, which may be impacted by pricing and reimbursement decisions relating to LEQEMBI, which are made by Eisai and/or third parties;

  • Biogen's ability to obtain and maintain adequate reimbursement for SKYCLARYS; and

  • the effectiveness of Biogen's commercial strategy for marketing SKYCLARYS.

Our long-term success depends upon the successful development of new products and additional indications for our existing products.

Our long-term success depends upon the successful development of new products from our research and development activities or our licenses or acquisitions from third parties, as well as the development of additional indications for our existing products. Product development is very expensive and involves a high degree of uncertainty and risk and is not always successful. Only a small number of research and development programs result in the commercialization of a product. It is difficult to predict the success and the time and cost of product development of novel approaches for the treatment of diseases. The development of novel approaches for the treatment of diseases, including development efforts in new modalities such as those based on the ASO platform, presents additional challenges and risks, including obtaining approval from regulatory authorities that have limited experience with the development of such therapies. For example, we are currently seeking approval of a subcutaneous formulation of LEQEMBI as a starting dose in the U.S. and any delays or challenges may impact our ability to realize the anticipated benefits from LEQEMBI.

Clinical trial data are subject to differing interpretations and even if we view data as sufficient to support the safety, effectiveness and/or approval of a product candidate, regulatory authorities may disagree and may require additional data, limit the scope of the approval or deny approval altogether. Furthermore, the approval of a product candidate by one regulatory agency does not mean that other regulatory agencies will also approve such product candidate.

Success in preclinical work or early stage clinical trials does not ensure that later stage or larger scale clinical trials will be successful. Clinical trials may indicate that our product candidates lack efficacy, have harmful side effects, result in unexpected adverse events or raise other concerns that may significantly reduce or delay the likelihood of regulatory approval. This may result in terminated programs, significant restrictions on use, safety warnings in an approved label, adverse placement within the treatment paradigm or significant reduction in the commercial potential of the product candidate.

Even if we could successfully develop new products or additional indications for our existing products, we may make a strategic decision to discontinue development of a product candidate or an additional indication for our existing products if, for example, we believe commercialization will be difficult relative to the standard of care or we prioritize other opportunities in our pipeline.

If we fail to compete effectively, our business and market position would suffer.

The biopharmaceutical industry and the markets in which we operate are intensely competitive. We compete in the marketing and sale of our products, the development of new products and processes, the acquisition of rights to new products with commercial potential and the hiring and retention of personnel. We compete with companies that have a greater number of products on the market and in the product pipeline, substantially greater financial, marketing, research and development and other resources, and other technological or competitive advantages.

Our products continue to face increasing competition from the introduction of new originator therapies, generics, prodrugs and biosimilars of existing products and products approved under abbreviated regulatory pathways. Some of these products are likely to be sold at substantially lower prices than our branded products. The introduction of such products as well as other lower-priced competing products has in the past reduced, and may in the future significantly reduce, both the price that we are able to charge for our products and the volume of products we sell, which has and may continue to negatively impact our revenue. In addition, in some markets, when a generic or biosimilar version of one of our products is commercialized, it has in the past and may in the future be automatically substituted for our product and significantly reduce our revenue in a short period of time.

Our ability to compete, maintain and grow our business may be adversely affected by a number of factors, including:

  • the introduction of other products, including products that may be more efficacious, safer, less expensive or more convenient alternatives to our products, including our own products and products of our collaborators;

  • the off-label use by physicians of therapies indicated for other conditions to treat patients;

  • patient dynamics, including the size of the patient population and our ability to identify, attract and maintain new and current patients to our therapies;

  • the reluctance of physicians to prescribe, and patients to use, our products without additional data on the efficacy and safety of such products;

  • damage to physician and pa

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Item 1B. UNRESOLVED STAFF COMMENTS

None.

Item 1C. CYBERSECURITY

RISK MANAGEMENT AND STRATEGY

We maintain a technology and cybersecurity program, which includes information security, as part of our overall risk management process with the aim that our information systems, including those of our vendors and other third parties, will be resilient, effective and capable of safeguarding against emerging risks and cybersecurity threats. We endeavor to assure our program is appropriately resourced and to attract and retain expert talent to execute it.

In designing, operating, evaluating and maintaining our program we use internal and external resources and frameworks, including cybersecurity expert consultants, industry working groups, the U.S. NIST Cybersecurity Framework and the U.S. Cybersecurity Agency's National Cyber Incident Scoring System model to benchmark, inform and evaluate the design of our program, our operational capabilities and our program maturity.

We have designed our cybersecurity policies and procedures to align with international regulatory frameworks, including the NIS2 Directive in the E.U. Our program integrates periodic reviews and updates to ensure our controls remain effective and compliant with evolving international regulations.

Consistent with NIST 800-53, our technology and cybersecurity program and controls include a third party and vendor risk management component. As part of our vendor risk management program, we conduct security assessments prior to engagement of high-risk vendors and other third-party providers and have a monitoring program to evaluate ongoing compliance with our cybersecurity standards.

A key element of our technology and cybersecurity program strategy is fostering training and awareness. Our training and awareness program includes annual cybersecurity awareness training and role-based phishing tests for our employees and for third parties with access to our systems.

Our technology and cybersecurity program focuses on the defense, rapid detection and rapid remediation of cybersecurity threats and incidents. Our program includes systems and processes designed based on defense-in-depth and zero-trust architectural principles and that are intended to provide the control capabilities set forth in NIST's 800-53 Rev 5, Security and Privacy Controls for Information Systems and Organizations. Our program also includes cybersecurity policies and a crisis response and management plan that is intended to allow rapid management and response and appropriate communication of cybersecurity threats and incidents.

We staff a cybersecurity operations center to respond to threats and incidents. Our cybersecurity crisis management plan sets forth the items, procedures and actions we expect to address and follow in the event of a cybersecurity incident, including detection, response, mitigation and remediation. In addition to the cybersecurity operations center and our designated cybersecurity response team, we maintain a cross-functional cybersecurity crisis core team, which includes our CISO and senior representatives from our Legal, Finance, IT and Corporate Security teams.

When a potential threat or incident is identified, our cyber security incident response team will assign a risk level classification and initiate the escalation and other steps called for by our plan. All incidents that are initially assessed by the cybersecurity incident response team as potentially high-risk are escalated promptly to our CISO. Our CISO, Chief Legal Officer and Chief Financial Officer, will determine whether and what elements of our cybersecurity crisis response and management plan should be activated, including escalation to other senior management or our Executive Committee. Our Executive Committee will inform our Board of Directors of cybersecurity incidents, as appropriate, considering a variety of factors, including financial, operational, legal or reputational impact.

Our program's maturity and operational readiness are regularly evaluated by internal audit and independent experts using the U.S. NIST's CyberSecurity Framework and penetration tests. Our program, and the results of these independent evaluations and testing, are regularly reviewed by our senior management and members of our Board of Directors.

CYBERSECURITY RISK GOVERNANCE

We are committed to appropriate cybersecurity governance and oversight. Our technology and cybersecurity program is the principal responsibility of our Chief Information Officer and CISO, each of whom have over 20 years of

experience in information systems, including cybersecurity training and experience. Additionally, we have a Cybersecurity steering committee that includes senior representatives from our Legal, Finance and IT departments, which meets regularly to discuss cybersecurity matters.

Our Board of Directors oversees management's processes for identifying and mitigating risks, including cybersecurity and information security risks. Our Board of Directors regularly reviews our technology and cybersecurity program and effectiveness, internal audits of our program, independent external expert evaluations of our program's maturity and operational readiness and the results of penetration testing. Our Board of Directors also receives cybersecurity updates and education on a broad range of topics, including:

  • Current cybersecurity landscape and emerging threats;

  • Status of ongoing cybersecurity initiatives and strategies;

  • Incident report and learnings from any cybersecurity events; and

  • Compliance with regulatory requirements and industry standards, including international regulations such as the NIS2 Directive in the E.U.

We do not believe that any risks from cybersecurity threats have materially affected or are reasonably likely to materially affect our business strategy, results of operations or financial condition during the period covered by this filing. For additional information on our cybersecurity risks, please read Item 1A. Risk Factors - A breakdown or breach of our information systems could subject us to liability or interrupt the operation of our business operations, included in this report.

Item 2. PROPERTIES

Below is a summary of our significant properties owned and leased as of December 31, 2025.

LocationApproximate Square FeetUseOwned/Leased
U.S.
Cambridge, Massachusetts263,000Research laboratory and cogeneration plantOwned
Cambridge, Massachusetts729,000Corporate headquarters and laboratoryLeased - Expires 2028
RTP, North Carolina1,237,000Office, laboratory, manufacturing, warehouseOwned
Durham, North Carolina40,000WarehouseLeased - Expires 2030
Plano, Texas327,000Office and laboratoryLeased - Expires 2038
International(1)
Solothurn, Switzerland734,000Manufacturing facility, warehouse and officeOwned
Baar, Switzerland81,800International headquartersLeased - Expires 2028
Athlone, Ireland47,500Fill finish manufacturing facilityLeased - Expires 2047

(1) We also lease office space in other international regions including: the U.K.; Germany; France; Japan; Canada and numerous other countries. Our international lease agreements expire at various dates through the year 2047.

In the fourth quarter of 2021 we began construction of a new clinical packaging and other manufacturing facility in RTP, North Carolina to support our R&D pipeline across multiple therapeutic areas. The new manufacturing facility is approximately 197,000 square feet. The construction of this manufacturing facility was completed during 2025 and the majority of the facility was placed in service during the fourth quarter of 2025.

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.

We believe that our existing properties, including both owned and leased sites, are adequate and suitable for the conduct of our business. We believe our capital resources are sufficient to purchase, lease or construct any additional facilities required to meet our expected long-term growth needs.

Item 3. LEGAL PROCEEDINGS

For a discussion of legal matters as of December 31, 2025, please read Note 21, Litigation, to our consolidated financial statements included in this report, which is incorporated into this item by reference.

Item 4. MINE SAFETY DISCLOSURES

Not applicable.

PART II

Item 5. MARKET FOR REGISTRANT'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

MARKET AND STOCKHOLDER INFORMATION

Our common stock trades on The Nasdaq Global Select Market under the symbol “BIIB.” As of February 4, 2026, there were approximately 372 shareholders of record of our common stock.

DIVIDENDS

We have not paid cash dividends since our inception. While we historically have not paid cash dividends and do not have a current intention to pay cash dividends, we continually review our capital allocation strategies, including, among other things, payment of cash dividends, share repurchases and acquisitions.

ISSUER PURCHASES OF EQUITY SECURITIES

The following table summarizes our common stock repurchase activity during the fourth quarter of 2025:

PeriodTotal Number of Shares Purchased (#)Average Price Paid per Share ($)Total Number of Shares Purchased as Part of Publicly Announced Programs (#)Approximate Dollar Value of Shares That May Yet Be Purchased Under Our Programs ($ in millions)
October 1, 2025 - October 31, 2025—$——$2,050.0
November 1, 2025 - November 30, 2025—$——$2,050.0
December 1, 2025 - December 31, 2025—$——$2,050.0
Total(1)—$—

(1) There were no share repurchases during the fourth quarter of 2025.

In October 2020 our Board of Directors authorized our 2020 Share Repurchase Program, which is a program to repurchase up to $5.0 billion of our common stock. Our 2020 Share Repurchase Program does not have an expiration date. All shares repurchased under our 2020 Share Repurchase Program were retired. There were no repurchases of our common stock during the years ended December 31, 2025, 2024 and 2023. Approximately $2.1 billion remained available under our 2020 Share Repurchase Program as of December 31, 2025.

PERFORMANCE GRAPH

The performance graph below compares the five-year cumulative total stockholder return on our common stock, the Nasdaq Pharmaceutical Index, the S&P 500 Index and the Nasdaq Biotechnology Index. The performance graph below assumes the investment of $100.00 on December 31, 2020, in our common stock and each of the three indexes, with dividends being reinvested.

The stock price performance in the graph below is not necessarily indicative of future price performance.

2013

202020212022202320242025
Biogen Inc.$100.00$97.98$113.08$105.65$62.43$71.84
Nasdaq Pharmaceutical Index$100.00$124.39$138.51$143.88$156.19$200.89
S&P 500 Index$100.00$128.71$105.40$133.10$166.40$196.16
Nasdaq Biotechnology Index$100.00$100.02$89.90$94.03$93.49$124.75

The information included under the heading Performance Graph is “furnished” and not “filed” for purposes of Section 18 of the Securities Exchange Act, or otherwise subject to the liabilities of that section, nor shall it be deemed to be “soliciting material” subject to Regulation 14A or incorporated by reference in any filing under the Securities Act of 1933 or the Securities Exchange Act of 1934.

Item 6. RESERVED

Item 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion should be read in conjunction with our consolidated financial statements and the accompanying notes beginning on page F-1 of this report.

For our discussion of the year ended December 31, 2024, compared to the year ended December 31, 2023, please read Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations located in our Annual Report on Form 10-K for the year ended December 31, 2024.

EXECUTIVE SUMMARY

INTRODUCTION

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.

We seek to ensure an uninterrupted supply of medicines to patients around the world. To that end, we regularly review our manufacturing capacity, capabilities, processes and facilities. In order to support our future growth and drug development pipeline, we expanded our large molecule production capacity and built a large-scale biologics manufacturing facility in Solothurn, Switzerland. The Solothurn facility is operational and has been approved for the manufacture of LEQEMBI and TYSABRI. We believe that the Solothurn facility will support our anticipated near to mid-term needs for the manufacturing of biologic assets. The plant represents a significant increase in our overall manufacturing capacity. Additionally, we continue to invest to modernize, automate and support the capacity requirements for our pipeline and existing products at our existing manufacturing facilities in RTP. If we are unable to fully utilize our manufacturing facilities, we will incur additional excess capacity charges which would have a negative effect on our financial condition and results of operations.

In the longer term, our revenue growth will depend upon the successful clinical development, regulatory approval and launch of new commercial products as well as additional indications for our existing products, our ability to obtain and maintain patents and other rights related to our marketed products, assets originating from our research and development efforts and/or successful execution of external business development opportunities.

BUSINESS ENVIRONMENT

For a detailed discussion on our business environment, please read Item 1. Business, included in this report. For additional information on our competition and pricing risks that could negatively impact our product sales, please read Item 1A. Risk Factors, included in this report.

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.

For additional information, please read Note 21, Litigation, to our consolidated financial statements included in this report.

TYSABRI

A biosimilar entrant of TYSABRI was approved in the U.S. and the E.U. in 2023. We expect the future sales of TYSABRI will continue to be adversely affected by the entrance of this biosimilar.

GOODWILL

We review our goodwill for impairment annually, as of October 31, and whenever events or changes in circumstances indicate that the carrying value of the goodwill may not be recoverable. As part of this analysis, we compare the fair value of our one reporting unit to its carrying value through the assessment of qualitative, and, if necessary, quantitative factors. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of our reporting unit, we will record an impairment loss equal to the difference. As of our most recent annual impairment analysis, we had no accumulated impairment losses related to goodwill.

An interim goodwill impairment test based on quantitative factors may be required if adverse events indicate an impairment might be present. We monitor changes to our stock price between annual impairment tests, and we believe that general deterioration in macroeconomic and industry-specific conditions may not be indicators of a goodwill impairment, as such conditions may not represent a significant adverse change to our underlying operating performance, cash flows, financial condition or liquidity. Should our market capitalization decline below the carrying value of our net assets for a sustained period, we would consider the length and severity of the decline and the reason for the decline when assessing whether potential goodwill impairment exists.

For additional information on goodwill, please read Note 7, Intangible Assets and Goodwill, to our consolidated financial statements included in this report.

INTERNATIONAL TRADE

Global disputes and interruptions in international relationships, including tariffs, trade protection measures, embargoes, import or export licensing requirements and the imposition of trade sanctions or similar restrictions, may affect our ability to do business and the costs that we incur in providing products to our patients.

The U.S. has imposed a baseline tariff on imports from all countries, subject to certain exceptions. Trade-related tensions between the U.S. and China have led to a series of tariffs and sanctions being imposed by the U.S. on imports from China and retaliatory tariffs imposed by China on U.S. imports.

The U.S. Secretary of Commerce has further initiated an investigation to determine the effects on the national security of imports of pharmaceuticals and phar

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Item 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

We are subject to certain risks that may affect our results of operations, cash flow and fair values of assets and liabilities, including volatility in foreign currency exchange rates, interest rate movements and equity price exposure as well as changes in economic conditions in the markets in which we operate as a result of the conflict between Russia and Ukraine and the military conflict in the Middle East. We manage the impact of foreign currency exchange rates and interest rates through various financial instruments, including derivative instruments such as foreign currency forward contracts, foreign currency options, interest rate lock contracts and interest rate swap contracts. We do not enter into financial instruments for trading or speculative purposes. The counterparties to these contracts are major financial institutions, and there is no significant concentration of exposure with any one counterparty.

FOREIGN CURRENCY EXCHANGE RISK

Our results of operations are subject to foreign currency exchange rate fluctuations due to the global nature of our operations. As a result, our consolidated financial position, results of operations and cash flow can be affected by market fluctuations in foreign currency exchange rates, primarily with respect to the Euro, British pound sterling, Canadian dollar, Swiss franc and the Polish złoty.

While the financial results of our global activities are reported in U.S. dollars, the functional currency for most of our foreign subsidiaries is their respective local currency. Fluctuations in the foreign currency exchange rates of the countries in which we do business will affect our operating results, often in ways that are difficult to predict. In particular, as the U.S. dollar strengthens versus other currencies, the value of the non-U.S. revenue will decline when reported in U.S. dollars. The impact to net income as a result of a strengthening U.S. dollar will be partially mitigated by the value of non-U.S. expense, which will also decline when reported in U.S. dollars. As the U.S. dollar weakens versus other currencies, the value of the non-U.S. revenue and expense will increase when reported in U.S. dollars.

We have established revenue and operating expense hedging and balance sheet risk management programs to protect against volatility of future foreign currency cash flow and changes in fair value caused by volatility in foreign currency exchange rates.

During the second quarter of 2018 the International Practices Task Force of the Center for Audit Quality categorized Argentina as a country with a projected three-year cumulative inflation rate greater than 100.0%, which indicated that Argentina’s economy is highly inflationary. This categorization did not have a material impact on our results of operations or financial position as of December 31, 2025, and is not expected to have a material impact on our results of operations or financial position in the future.

REVENUE AND OPERATING EXPENSE HEDGING PROGRAM

Our foreign currency hedging program is designed to mitigate, over time, a portion of the impact resulting from volatility in exchange rate changes on revenue and operating expense. We use foreign currency forward contracts and foreign currency options to manage foreign currency risk, with the majority of our forward contracts and options used to hedge certain forecasted revenue and operating expense transactions denominated in foreign currencies in the next 21 months. We do not engage in currency speculation. For a more detailed disclosure of our revenue and operating expense hedging program, please read Note 10, Derivative Instruments, to our consolidated financial statements included in this report.

Our ability to mitigate the impact of foreign currency exchange rate changes on revenue and net income diminishes as significant foreign currency exchange rate fluctuations are sustained over extended periods of time. In particular, devaluation or significant deterioration of foreign currency exchange rates are difficult to mitigate and likely to negatively impact earnings. The cash flow from these contracts are reported as operating activities in our consolidated statements of cash flow.

BALANCE SHEET RISK MANAGEMENT HEDGING PROGRAM

We also use forward contracts to mitigate the foreign currency exposure related to certain balance sheet items. The primary objective of our balance sheet risk management program is to mitigate the exposure of foreign currency denominated net monetary assets and liabilities of foreign affiliates. In these instances, we principally utilize

currency forward contracts. We have not elected hedge accounting for the balance sheet related items. The cash flow from these contracts are reported as operating activities in our consolidated statements of cash flow.

The following quantitative information includes the impact of currency movements on forward contracts used in our revenue, operating expense and balance sheet hedging programs. As of December 31, 2025 and 2024, a hypothetical adverse 10.0% movement in foreign currency exchange rates compared to the U.S. dollar across all maturities would result in a hypothetical decrease in the fair value of forward contracts of approximately $278.0 million and $191.7 million, respectively. The estimated fair value change was determined by measuring the impact of the hypothetical exchange rate movement on outstanding forward contracts. Our use of this methodology to quantify the market risk of such instruments is subject to assumptions and the actual impact could be significantly different. The quantitative information about market risk is limited because it does not take into account all foreign currency operating transactions.

CREDIT RISK

Financial instruments that potentially subject us to concentrations of credit risk include cash and cash equivalents, investments, derivatives and accounts receivable. We attempt to minimize the risks related to cash and cash equivalents and investments by investing in a broad and diverse range of financial instruments. We have established guidelines related to credit ratings and maturities intended to safeguard principal balances and maintain liquidity. Our investment portfolio is maintained in accordance with our investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer. We minimize credit risk resulting from derivative instruments by choosing only highly rated financial institutions as counterparties.

We operate in certain countries where weakness in economic conditions, including the effects of the conflict between Russia and Ukraine and the military conflict in the Middle East, can result in extended collection periods. We continue to monitor these conditions, including the volatility associated with international economies and the relevant financial markets, and assess their possible impact on our business. To date, we have not experienced any significant losses with respect to the collection of our accounts receivable.

We believe that our allowance for doubtful accounts was adequate as of December 31, 2025 and 2024.

Item 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

The information required by this Item 8 is contained on pages F-1 through F-79 of this report and is incorporated herein by reference.

Item 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

None.

Item 9A. CONTROLS AND PROCEDURES

DISCLOSURE CONTROLS AND PROCEDURES AND INTERNAL CONTROL OVER FINANCIAL REPORTING

CONTROLS AND PROCEDURES

We have carried out an evaluation, under the supervision and with the participation of our management, including our principal executive officer and principal financial officer, of the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rules 13a-15(e) or 15d-15(e) under the Securities Exchange Act of 1934, as amended), as of December 31, 2025. Based upon that evaluation, our principal executive officer and principal financial officer concluded that, as of the end of the period covered by this report, our disclosure controls and procedures are effective in ensuring that:

(a) the information required to be disclosed by us in the reports that we file or submit under the Securities Exchange Act is recorded, processed, summarized and reported within the time periods specified in the U.S. Securities and Exchange Commission's rules and forms; and

(b) such information is accumulated and communicated to our management, including our principal executive officer and principal financial officer, as appropriate to allow timely decisions regarding required disclosure.

In designing and evaluating our disclosure controls and procedures, our management recognized that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives, and our management necessarily was required to apply its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

CHANGES IN INTERNAL CONTROL OVER FINANCIAL REPORTING

There were no changes in our internal control over financial reporting during the quarter ended December 31, 2025, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

MANAGEMENT'S ANNUAL REPORT ON INTERNAL CONTROL OVER FINANCIAL REPORTING

Our management is responsible for establishing and maintaining adequate internal control over our financial reporting. Internal control over financial reporting is defined in Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act as a process designed by, or under the supervision of, a company’s principal executive and principal financial officers and effected by a company’s board of directors, management and other personnel to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with U.S. GAAP. Our internal control over financial reporting includes those policies and procedures that:

  • pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect our transactions and dispositions of our assets;

  • provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with U.S. GAAP, and that our receipts and expenditures are being made only in accordance with authorizations of our management and directors; and

  • provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use or disposition of our assets that could have a material effect on our financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Our management assessed the effectiveness of our internal control over financial reporting as of December 31, 2025. In making this assessment, management used the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission (COSO) in its 2013 Internal Control — Integrated Framework.

Based on our assessment, our management has concluded that, as of December 31, 2025, our internal control over financial reporting is effective based on those criteria.

The effectiveness of our internal control over financial reporting as of December 31, 2025, has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their attestation report, which is included herein.

Item 9B. OTHER INFORMATION

TRADING ARRANGEMENTS

From time to time, our officers (as defined in Rule 16a-1(f)) and directors may enter into, amend or terminate Rule 10b5-1 or non-Rule 10b5-1 trading arrangements (as each such term is defined in Item 408 of Regulation S-K). During the fourth quarter of 2025 there were no trading arrangements for the purchase or sale of our securities entered into, amended or terminated by our officers and directors.

Item 9C. DISCLOSURE REGARDING FOREIGN JURISDICTIONS THAT PREVENT INSPECTIONS

Not Applicable.

PART III

Item 10. DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

The information concerning our executive officers is set forth under the heading Information about our Executive Officers in Item 1 of this report.

Code of Business Conduct and Ethics: The text of our code of business conduct, which includes the code of ethics that applies to our principal executive officer, principal financial officer, principal accounting officer or controller, and persons performing similar functions, is posted on our website, www.biogen.com, under the “Corporate Governance” subsection of the “Investors” section of the site. We intend to make all required disclosures regarding any amendments to, or waivers from, provisions of our code of business conduct at the same location of our website.

Insider Trading Policy: We have adopted an insider trading policy governing the purchase, sale and/or other dispositions of our securities and those of public companies in which we do business with by our directors, executive officers, employees and temporary staff, that we believe is reasonably designed to promote compliance with insider trading laws, rules and regulations and applicable NASDAQ listing standards. A copy of our insider trading policy is filed as Exhibit 19.1 to this Annual Report on Form 10-K.

The response to the remainder of this item is incorporated by reference from the discussion responsive thereto in the sections entitled “Proposal 1 - Election of Directors,” “Corporate Governance” and “Miscellaneous - Stockholder Proposals” contained in the proxy statement for our 2026 annual meeting of stockholders.

Item 11. EXECUTIVE COMPENSATION

The response to this item is incorporated by reference from the discussion responsive thereto in the sections entitled “Executive Compensation Tables,” "Compensation Discussion and Analysis" and “Corporate Governance” contained in the proxy statement for our 2026 annual meeting of stockholders.

Item 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS

The response to this item is incorporated by reference from the discussion responsive thereto in the sections entitled “Stock Ownership” and “Equity Compensation Plan Information” contained in the proxy statement for our 2026 annual meeting of stockholders.

Item 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE

The response to this item is incorporated by reference from the discussion responsive thereto in the sections entitled “Certain Relationships and Related Person Transactions” and “Corporate Governance” contained in the proxy statement for our 2026 annual meeting of stockholders.

Item 14. PRINCIPAL ACCOUNTANT FEES AND SERVICES

The response to this item is incorporated by reference from the discussion responsive thereto in the section entitled “Proposal 2 - Ratification of the Selection of our Independent Registered Public Accounting Firm” contained in the proxy statement for our 2026 annual meeting of stockholders.

PART IV

Item 15. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

a. (1) Consolidated Financial Statements:

The following financial statements are filed as part of this report:

Financial StatementsPage Number
Consolidated Statements of IncomeF-2
Consolidated Statements of Comprehensive IncomeF-3
Consolidated Balance SheetsF-4
Consolidated Statements of Cash FlowF-5
Consolidated Statements of EquityF-6
Notes to Consolidated Financial StatementsF-8
Report of Independent Registered Public Accounting Firm (PCAOB ID 238)F-80

Certain totals may not sum due to rounding.

(2) Exhibits

The exhibits listed on the Exhibit Index beginning on page 98, which is incorporated herein by reference, are filed or furnished as part of this report or are incorporated into this report by reference.

(3) Financial Statement Schedules

Schedules are omitted because they are not applicable, or are not required, or because the information is included in the consolidated financial statements and notes thereto.

Item 16. FORM 10-K SUMMARY

Not applicable.

EXHIBIT INDEX

Exhibit No.Description
2.1Agreement and Plan of Merger by and among Reata Pharmaceuticals, Inc., Biogen Inc. and River Acquisition, Inc. dated as of July 28, 2023. Filed as Exhibit 2.1 to our current report on Form 8-K filed July 31, 2023.
3.1Amended and Restated Certificate of Incorporation, as amended. Filed as Exhibit 3.1 to our Quarterly Report on Form 10-Q for the quarter ended June 30, 2012.
3.2Certificate of Amendment to the Certificate of Incorporation. Filed as Exhibit 3.1 to our Current Report on Form 8-K filed on March 27, 2015.
3.3Certificate of Amendment of Biogen Inc.'s Amended and Restated Certificate of Incorporation, as amended. Filed as Exhibit 3.1 to our Current Report on Form 8-K filed on June 8, 2021.
3.4Certificate of Amendment of Biogen Inc.'s Amended and Restated Certificate of Incorporation, as amended. Filed as Exhibit 3.1 to our Current Report on Form 8-K filed on June 25, 2024.
3.5Fifth Amended and Restated Bylaws of Biogen Inc. Filed as Exhibit 3.1 to our Current Report on Form 8-K filed on December 12, 2023.
4.1Second Supplemental Indenture, dated April 30, 2020, between Biogen Inc. and U.S. Bank National Association, including the forms of Global Notes attached as Exhibit A and Exhibit B, respectively, thereto. Filed as Exhibit 4.2 to our Current Report on Form 8-K filed on April 30, 2020.
4.2Reference is made to Exhibit 3.1 for a description of the rights, preferences and privileges of our Series A Preferred Stock and Series X Junior Participating Preferred Stock.
4.3Indenture between Biogen Inc. and U.S. Bank National Association, dated as of September 15, 2015. Filed as Exhibit 4.1 to our Current Report on Form 8-K filed on September 16, 2015.
4.4First Supplemental Indenture between Biogen Inc. and U.S. Bank National Association, dated September 15, 2015. Filed as Exhibit 4.2 to our Current Report on Form 8-K filed on September 16, 2015.
4.5Third Supplemental Indenture, dated February 16, 2021, between Biogen Inc. and U.S. Bank National Association. Filed as Exhibit 4.2 to our Current Report on Form 8-K filed on February 16, 2021.
4.6Fourth Supplemental Indenture, dated as of May 12, 2025, between the Company and U.S. Bank Trust Company, National Association (as successor to U.S. Bank, National Association), including the forms of Global Notes attached as Exhibit A, Exhibit B and Exhibit C, respectively, thereto. Filed as Exhibit 4.2 to our Current Report on Form 8-K filed on May 12, 2025.
4.7Description of Securities. Filed as Exhibit 4.6 to our Annual Report on Form 10-K for the year ended December 31, 2023.
10.1Credit Agreement, dated as of August 12, 2024, among Biogen Inc., Bank of America, N.A., as administrative agent, swing line lender and the L/C issuer, and the other lenders party thereto. Filed as Exhibit 10.1 to our Current Report on Form 8-K filed on August 14, 2024.
10.2Credit Agreement, dated as of August 28, 2023, among Biogen Inc., JPMorgan Chase Bank N.S., as administrative agent and the other lenders party thereto. Filed as Exhibit 10.1 to our Current Report on Form 8-K filed on September 1, 2023.
10.3†Second Amended and Restated Collaboration Agreement between Biogen Idec Inc. and Genentech, Inc., dated as of October 18, 2010. Filed as Exhibit 10.5 to our Annual Report on Form 10-K for the year ended December 31, 2010.
10.4†Letter Agreement regarding GA101 financial terms between Biogen Idec Inc. and Genentech, Inc., dated October 18, 2010. Filed as Exhibit 10.6 to our Annual Report on Form 10-K for the year ended December 31, 2010.
10.5Form of performance share award agreement under the Biogen Inc. 2024 Omnibus Equity Plan. Filed as Exhibit 10.3 to our Quarterly Report on Form 10-Q for the quarter ended June 30, 2024.
10.6Form of restricted stock award agreement under the Biogen Inc. 2024 Omnibus Equity Plan. Filed as Exhibit 10.4 to our Quarterly Report on Form 10-Q for the quarter ended June 30, 2024.
10.7Form of non-employee director restricted stock unit award agreement under the Biogen Inc. 2024 Omnibus Equity Plan. Filed as Exhibit 10.5 to our Quarterly Report on Form 10-Q for the quarter ended June 30, 2024.
10.8*Biogen Inc. 2017 Omnibus Equity Plan. Filed as Appendix B to our Definitive Proxy Statement on Schedule 14A filed on April 26, 2017.
10.9*Form of restricted stock unit award agreement under the Biogen Inc. 2017 Omnibus Equity Plan. Filed as Exhibit 10.2 to our Quarterly Report on Form 10-Q for the quarter ended June 30, 2017.
10.10*Form of performance stock units award agreement under the Biogen Inc. 2017 Omnibus Equity Plan (for grants commencing in July 2019). Filed as Exhibit 10.2 to our Quarterly Report on Form 10-Q for the quarter ended June 30, 2019.
10.11*Form of nonqualified stock option award agreement under Biogen Inc. 2017 Omnibus Equity Plan. Filed as Exhibit 10.20 to our Annual Report on Form 10-K for the year ended December 31, 2022.
10.12*[Biogen Idec Inc. 2008 Performance

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