UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-Q


☒			QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended ~~June~~September 30, 2025


☐			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

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

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. o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No x

The number of shares of the issuer’s Common Stock, $0.0005 par value, outstanding as of ~~July~~October 2928, 2025, was 146,~~614~~702,~~598~~272 shares.

Table of Contents

BIOGEN INC.

FORM 10-Q — Quarterly Report

For the Quarterly Period Ended ~~June~~September 30, 2025

TABLE OF CONTENTS

		Page
PART I — FINANCIAL INFORMATION
Item 1.	Financial Statements (unaudited)
	Condensed Consolidated Statements of Income — For the Three and Six Months Ended June 30, 2025 and 2024	8
	Condensed Consolidated Statements of Income — For the Three and Nine Months Ended September 30, 2025 and 2024	8
	Condensed Consolidated Statements of Comprehensive Income — For the Three and Six Months Ended June 30, 2025 and 2024	9
	Condensed Consolidated Statements of Comprehensive Income — For the Three and Nine Months Ended September 30, 2025 and 2024	9
	Condensed Consolidated Balance Sheets — As of June 30, 2025 and December 31, 2024	10
	Condensed Consolidated Balance Sheets — As of September 30, 2025 and December 31, 2024	10
	Condensed Consolidated Statements of Cash Flow — For the Six Months Ended June 30, 2025 and 2024	11
	Condensed Consolidated Statements of Cash Flow — For the Nine Months Ended September 30, 2025 and 2024	11
	Condensed Consolidated Statements of Equity — For the Three and Six Months Ended June 30, 2025 and 2024	12
	Condensed Consolidated Statements of Equity — For the Three and Nine Months Ended September 30, 2025 and 2024	12
	Notes to Condensed Consolidated Financial Statements	14
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	5054
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	7884
Item 4.	Controls and Procedures	8086
PART II — OTHER INFORMATION
Item 1.	Legal Proceedings	8087
Item 1A.	Risk Factors	8187
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	96103
Item 5.	Other Information	96103
Item 6.	Exhibits	97104
Signatures		98105

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 continued 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;

•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 in the U.S. and international markets and a biosimilar entrant of TYSABRI;

•patent terms, patent term extensions, patent office actions and expected availability and periods of regulatory ~~exclusivity~~exclusivities, as well as our ability to adequately enforce existing patents, including our European patent related to TECFIDERA;

•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 nusinersen;

Table of Contents

•~~the successful execution of~~ our ~~strategic~~ability ~~and~~to ~~growth~~effectively ~~initiatives,~~implement ~~including acquisitions, and~~ our ~~ability~~corporate tostrategy ~~realize~~which ~~the~~includes ~~anticipated~~significant ~~benefits~~investment ~~from~~in ~~our~~product ~~acquisitions of Reata~~ and ~~HI-Bio~~pipeline candidates, including ~~future~~but ~~performance~~not oflimited ~~the~~to ~~SKYCLARYS product and further development of the~~ felzartamab, ~~product~~litifilimab and ~~anticipated synergies~~nusinersen;

•the successful execution of our strategic and growth initiatives, including acquisitions, and our ability to realize the anticipated benefits from our acquisitions of Reata and HI-Bio and the potential acquisition of Alcyone, including future performance of the SKYCLARYS product, further development of the felzartamab product, future development of drug delivery solutions and anticipated synergies;

•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 ~~Sage~~Supernus, as well as the potential therapeutic scope of the development and commercialization of our and our collaborators’ pipeline 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, pre-clinical 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., China and other countries, regions affected by Russia's invasion of Ukraine and the military conflict in the Middle East;

•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 the MFN drug pricing policy;

•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 facility, activities in new or existing manufacturing facilities and the expected timeline

Table of Contents

•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;

•changes in our effective tax rate and obligations in various jurisdictions in which we are subject to taxation; and

•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.

These forward-looking statements involve risks and uncertainties, including those that are described in Part II, Item 1A. Risk Factors and Part I, Item 2. 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 our 2024 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®, BYOOVIZ®, PLEGRIDY®, QALSODY®, RITUXAN®, RITUXAN HYCELA®, SKYCLARYS®, SPINRAZA®, TECFIDERA®, TYSABRI® and VUMERITY® are registered trademarks of Biogen.

BENEPALI™, FLIXABI™, FUMADERM™, IMRALDI™ and OPUVIZ™ are trademarks of Biogen.

ACTEMRA®, COLUMVI®, ENBREL®, EYLEA®, GAZYVA®, LEQEMBI®, HUMIRA®, LUCENTIS®, LUNSUMIO®, OCREVUS®, REMICADE®, ZURZUVAE™ and other trademarks referenced in this report are the property of their respective owners.

NOTE REGARDING DISCLOSURES

From time to time, we have used, or expect in the future to use, our investor relations website (investors.biogen.com), the Biogen LinkedIn account (linkedin.com/company/biogen) and the Biogen X account (https://x.com/biogen) as a means of disclosing information to the public in a broad, non-exclusionary manner, including for purposes of the SEC’s Regulation Fair Disclosure (Reg FD). Accordingly, investors should monitor our investor relations website and these social media channels in addition to our press releases, SEC filings, public conference calls and websites, as the information posted on them could be material to investors.

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 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
2025 Senior Notes			Senior Unsecured Notes Issued in May 2025
AbbVie			AbbVie Inc.
AI			Artificial Intelligence
Alcyone			Alcyone Therapeutics, Inc.
ALS			Amyotrophic Lateral Sclerosis
AMR			Antibody-Mediated Rejection
AOCI			Accumulated Other Comprehensive Income (Loss)
ASO			Antisense Oligonucleotide
ASU			Accounting Standards Update
BLA			Biologics License Application
CCPA			California Consumer Privacy Act
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
DEA			Drug Enforcement Agency
Denali			Denali Therapeutics Inc.
District Court			U.S. District Court for the District of Massachusetts
DOJ			U.S. Department of Justice
EC			European Commission
Eisai			Eisai Co., Ltd.
EMA			European Medicines Agency
E.U.			European Union
FA			Friedreich Ataxia
FASB			Financial Accounting Standards Board
FCPA			Foreign Corrupt Practices Act
FDA			U.S. Food and Drug Administration
Fit for Growth			Cost saving program initiated in 2023
G7			Group of Seven (comprised of Canada, France, Germany, Italy, Japan, the U.K. and the U.S.)
Genentech			Genentech, Inc.
GILTI			Global Intangible Low Tax 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
IPR&D			In-process Research and Development
IRA			Inflation Reduction Act of 2022
IT			Information Technology

Table of Contents

DEFINED TERMS (continued)

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
MAA			Marketing Authorization Application
MDD			Major Depressive Disorder
MorphoSys			MorphoSys AG
MFN			Most-Favored-Nation
MS			Multiple Sclerosis
NDA			New Drug Application
Neurimmune			Neurimmune SubOne AG
OBBBA			One Big Beautiful Bill Act
OECD			Organization for Economic Co-operation and Development
ODD			Orphan Drug Designation
Organon			Organon LLC
PDUFA			Prescription Drug User Fee Act
PMN			Primary Membranous Nephropathy
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.
RMS			Relapsing MS
RNAi			RNA interference
RRMS			Relapsing-Remitting MS
RTP			Research Triangle Park
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
SOD1			Superoxide Dismutase 1
Supernus			Supernus Pharmaceuticals, Inc.
SWISSMEDIC			Swiss Agency for Therapeutic Products
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			Veterans Affairs
Vanqua			Vanqua Bio, Inc.
VAT			Value-added Tax

Table of Contents

PART I FINANCIAL INFORMATION

BIOGEN INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(unaudited, in millions, except per share amounts)

For the Three Months Ended June 30,

For the Six Months Ended June 30,

For the Three Months Ended September 30,

For the Nine Months Ended September 30,

2025

2024

2025

2024

Revenue:

Product revenue, net

1,~~878~~846.79

1,~~899~~769.64

35,~~605~~452.21

35,~~611~~380.59

Revenue from anti-CD20 therapeutic programs

~~467~~493.39

~~444~~446.52

~~845~~1,339.54

~~838~~1,284.57

Alzheimer's collaboration revenue

5442.97

1118.86

87130.96

1433.62

Contract manufacturing, royalty and other revenue

~~244~~151.62

~~109~~231.06

~~537~~689.91

~~290~~522.84

Total revenue

2,~~645~~534.57

2,~~464~~465.98

57,~~076~~611.52

47,~~755~~221.42

Cost and expense:

Cost of sales, excluding amortization and impairment of acquired intangible assets

~~605~~674.04

~~546~~638.07

1,~~234~~908.37

1,~~088~~726.29

Research and development

~~399~~436.01

~~505~~516.42

~~833.~~1,269.2

~~950~~1,467.80

Acquired in-process research and development, upfront and milestone expense

462.61

826.5

~~247~~249.34

1642.05

Selling, general and administrative

~~583~~594.8

~~553~~588.84

1,~~156~~751.31

1,~~135~~723.37

Amortization and impairment of acquired intangible assets

~~130~~135.97

86130.93

~~242~~378.74

~~165~~295.25

Collaboration profit sharing/(loss reimbursement)

7587.02

6269.43

~~133~~220.13

~~128~~197.03

(Gain) loss on fair value remeasurement of contingent consideration

135.26

—23.8

2228.84

—23.8

Restructuring charges

~~(0.~~7).4

6.68

3442.60

1824.19

Gain on sale of priority review voucher, net

—

~~(88.6)~~—

—

(88.6)

Other (income) expense, net

4834.71

8514.28

~~117~~151.12

~~178~~193.97

Total cost and expense

1,~~901~~977.54

12,~~766~~014.28

45,~~021~~998.37

35,~~591~~606.97

Income before income tax (benefit) expense

~~744~~557.03

~~698~~451.70

1,~~055~~612.25

1,~~163~~614.5

Income tax (benefit) expense

~~109~~90.28

~~115~~62.15

~~179~~270.97

~~186~~249.50

Net income attributable to Biogen Inc.

~~634~~466.85

~~583~~388.65

~~875~~1,341.38

~~977~~1,365.05

Net income per share:

Basic earnings per share attributable to Biogen Inc.

43.3318

42.0167

59.9816

69.7238

Diluted earnings per share attributable to Biogen Inc.

43.3317

42.0066

59.9714

69.7035

Weighted-average shares used in calculating:

Basic earnings per share attributable to Biogen Inc.

146.56

145.67

146.34

145.45

Diluted earnings per share attributable to Biogen Inc.

~~146~~147.71

~~145~~146.91

146.78

~~145~~146.90

See accompanying notes to these unaudited condensed consolidated financial statements.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(unaudited, in millions)

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2025		2024		2025		2024
Net income attributable to Biogen Inc.	$	~~634~~466.85	$	~~583~~388.65	$	~~875~~1,341.38	$	~~977~~1,365.05
Other comprehensive income (loss):
Unrealized gains (losses) on cash flow hedges, net of tax	~~(105~~26.8)5		20(41.10)		(~~163~~137.61)		34(6.82)
Unrealized gains (losses) on pension benefit obligation, net of tax	~~0.6~~—		—0.3		1.0		(0.1)2
Currency translation adjustments, net of tax	41(3.62)		(541.6)0		6057.75		~~(27~~14.0)
Total other comprehensive income (loss), net of tax	~~(63~~23.6)3		140.53		(~~101~~78.96)		78.70
Comprehensive income (loss) attributable to Biogen Inc.	$	~~571~~489.28	$	~~598~~388.18	$	~~773~~1,263.42	$	~~984~~1,373.75

See accompanying notes to these unaudited condensed consolidated financial statements.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited, in millions, except per share amounts)

	As of June 30, 2025		As of December 31, 2024
	As of September 30, 2025		As of December 31, 2024
ASSETS
Current assets:
Cash and cash equivalents	$	23,~~758~~862.8	$	2,375.0
Accounts receivable, net of allowance for doubtful accounts of $2.9 and $2.2, respectively	1,624.2		1,404.8
Marketable securities	97.6		—
Due from anti-CD20 therapeutic programs	459.8		464.0
Accounts receivable, net of allowance for doubtful accounts of $3.1 and $2.2, respectively	1,374.1		1,404.8
Inventory	2,274.3		2,460.5
Due from anti-CD20 therapeutic programs	475.9		464.0
Other current assets	850.6		752.5
Inventory	2,209.4		2,460.5
Total current assets	7,967.7		7,456.8
Other current assets	916.8		752.5
Property, plant and equipment, net	3,098.8		3,181.3
Total current assets	8,936.6		7,456.8
Operating lease assets	334.5		356.4
Property, plant and equipment, net	3,075.7		3,181.3
Intangible assets, net	9,467.5		9,691.2
Operating lease assets	330.5		356.4
Goodwill	6,493.1		6,478.9
Intangible assets, net	9,331.9		9,691.2
Deferred tax asset	330.9		324.2
Goodwill	6,490.7		6,478.9
Investments and other assets	637.7		560.5
Deferred tax asset	312.4		324.2
Total assets	$	28,330.2	$	28,049.3
Investments and other assets	729.7		560.5
Total assets	$	29,207.5	$	28,049.3
LIABILITIES AND EQUITY
Current liabilities:
Current portion of notes payable	$	—	$	1,748.6
Taxes payable	~~114~~103.83		548.3
Accounts payable	~~408~~413.41		424.2
Accrued expense and other	2,~~660~~773.56		2,807.7
Total current liabilities	3,~~183~~290.70		5,528.8
Notes payable	6,~~283~~285.71		4,547.2
Deferred tax liability	~~118~~358.31		190.5
Long-term operating lease liabilities	~~310~~305.90		334.5
Other long-term liabilities	~~799~~761.68		732.3
Total liabilities	1011,~~696~~000.20		11,333.3
Commitments, contingencies and guarantees
Equity:
Biogen Inc. shareholders’ equity:
Preferred stock, par value $0.001 per share	—		—
Common stock, par value $0.0005 per share	0.1		0.1
Additional paid-in capital	~~714~~797.07		569.4
Accumulated other comprehensive income (loss)	(~~238~~214.18)		(136.2)
Retained earnings	20,~~135~~601.16		19,259.8
Treasury stock, at cost	(2,977.1)		(2,977.1)
Total equity	1718,~~634~~207.05		16,716.0
Total liabilities and equity	$	2829,~~330~~207.25	$	28,049.3

See accompanying notes to these unaudited condensed consolidated financial statements.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOW

(unaudited, in millions)

	For the Six Months Ended June 30,
	For the Nine Months Ended September 30,
	2025		2024
Cash flow from operating activities:
Net income	$	~~875~~1,341.38	$	~~977~~1,365.05
Adjustments to reconcile net income to net cash flow from operating activities:
Depreciation and amortization	~~377~~579.57		~~306~~489.42
Impairment of intangible assets	3.5		—20.2
Excess and obsolescence charges related to inventory	1413.39		4468.47
Amortization of acquired inventory step-up	~~103~~165.94		~~134~~185.21
Share-based compensation	~~155~~231.92		~~143~~216.41
Contingent consideration	2228.84		—23.8
Deferred income taxes	~~(59~~194.1)7		(4799.17)
(Gain) loss on strategic investments	33.27		6122.67
Gain on sale of priority review voucher, net	—		(88.6)
Other	1649.03		6595.01
Changes in operating assets and liabilities, net of effects of business acquired:
Accounts receivable	~~(170~~74.5)9		12127.36
Due from anti-CD20 therapeutic programs	4(11.28)		(15.19)
Inventory	(2735.93)		(~~188~~207.24)
Accrued expense and other current liabilities	(~~318~~32.7)		(~~115~~84.62)
Income tax assets and liabilities	(~~534~~764.71)		(762.7)1
Other changes in operating assets and liabilities, net	(75179.59)		(~~103~~65.07)
Net cash flow provided by (used in) operating activities	~~420~~1,692.27		12,~~179~~114.06
Cash flow from investing activities:
Purchases of property, plant and equipment	(63109.79)		(79114.4)
Purchases of marketable securities	(91.0)		—
Acquisition of HI-Bio, net of cash acquired	—		(1,074.8)
Proceeds from sale of equity interest in Samsung Bioepis	—		406.8
Proceeds from sale of priority review voucher	—		~~103~~88.06
Acquisitions of intangible assets	(1015.03)		(84179.1)
Proceeds from sales of strategic investments	—56.6		5796.57
Other	~~(30~~20.6)2		(34.34)
Net cash flow provided by (used in) investing activities	(~~104~~139.34)		~~400~~(780.56)
Cash flow from financing activities:
Payments related to issuance of stock for share-based compensation arrangements, net	(1813.20)		(4034.8)
Proceeds from borrowings	1,733.41		—
Repayments of borrowings	(1,750.0)		(650.0)
Other	0.1		6.0
Cash paid for contingent consideration	(141.3)		—
Net cash flow provided by (used in) financing activities	(34.7)		(684.8)
Other	6.3		(6.6)
Net increase (decrease) in cash and cash equivalents	281.2		894.7
Net cash flow provided by (used in) financing activities	(164.9)		(691.4)
Effect of exchange rate changes on cash and cash equivalents	102.6		(35.7)
Net increase (decrease) in cash and cash equivalents	1,388.4		642.6
Effect of exchange rate changes on cash and cash equivalents	99.4		6.7
Cash and cash equivalents, beginning of the period	2,375.0		1,049.9
Cash and cash equivalents, end of the period	$	23,~~758~~862.8	$	1,~~908~~699.92

See accompanying notes to these unaudited condensed consolidated financial statements.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY

(unaudited, in millions)

	For the Three Months Ended June 30, 2025
	For the Three Months Ended September 30, 2025
	Preferred stock			Common stock			Additionalpaid-incapital		Accumulatedothercomprehensiveincome (loss)		Retainedearnings		Treasury stock			Totalequity
	Shares	Amount		Shares	Amount								Shares	Amount
Balance, March 31, 2025	—	$	—	170.3	$	0.1	$	629.9	$	(174.5)	$	19,500.3	(23.8)	$	(2,977.1)	$	16,978.7
Net income	—	—		—	—		—		—		634.8		—	—		634.8
Other comprehensive income (loss), net of tax	—	—		—	—		—		(63.6)		—		—	—		(63.6)
Issuance of common stock under stock option and stock purchase plans	—	—		0.1	—		6.9		—		—		—	—		6.9
Issuance of common stock under stock award plan	—	—		—	—		(0.8)		—		—		—	—		(0.8)
Compensation related to share-based payments	—	—		—	—		78.1		—		—		—	—		78.1
Other	—	—		—	—		(0.1)		—		—		—	—		(0.1)
Balance, June 30, 2025	—	$	—	170.4	$	0.1	$	714.0	$	(238.1)	$	20,135.1	(23.8)	$	(2,977.1)	$	17,634.0
	For the Six Months Ended June 30, 2025
Net income	—	—		—	—		—		—		466.5		—	—		466.5
Other comprehensive income (loss), net of tax	—	—		—	—		—		23.3		—		—	—		23.3
Issuance of common stock under stock option and stock purchase plans	—	—		—	—		6.5		—		—		—	—		6.5
Issuance of common stock under stock award plan	—	—		0.1	—		(1.2)		—		—		—	—		(1.2)
Compensation related to share-based payments	—	—		—	—		78.4		—		—		—	—		78.4
Other	—	—		—	—		—		—		—		—	—		—
Balance, September 30, 2025	—	$	—	170.5	$	0.1	$	797.7	$	(214.8)	$	20,601.6	(23.8)	$	(2,977.1)	$	18,207.5
	For the Nine Months Ended September 30, 2025
	Preferred stock			Common stock			Additionalpaid-incapital		Accumulatedothercomprehensiveincome (loss)		Retainedearnings		Treasury stock			Totalequity
	Shares	Amount		Shares	Amount								Shares	Amount
Balance, December 31, 2024	—	$	—	169.5	$	0.1	$	569.4	$	(136.2)	$	19,259.8	(23.8)	$	(2,977.1)	$	16,716.0
Net income	—	—		—	—		—		—		~~875~~1,341.38		—	—		~~875~~1,341.38
Other comprehensive income (loss), net of tax	—	—		—	—		—		(~~101~~78.96)		—		—	—		(~~101~~78.96)
Issuance of common stock under stock option and stock purchase plans	—	—		0.3	—		2228.16		—		—		—	—		2228.16
Issuance of common stock under stock award plan	—	—		0.67	—		(4041.35)		—		—		—	—		(4041.35)
Compensation related to share-based payments	—	—		—	—		~~162~~240.26		—		—		—	—		~~162~~240.26
Other	—	—		—	—		0.6		—		—		—	—		0.6
Balance, June 30, 2025	—	$	—	170.4	$	0.1	$	714.0	$	(238.1)	$	20,135.1	(23.8)	$	(2,977.1)	$	17,634.0
Balance, September 30, 2025	—	$	—	170.5	$	0.1	$	797.7	$	(214.8)	$	20,601.6	(23.8)	$	(2,977.1)	$	18,207.5

See accompanying notes to these unaudited condensed consolidated financial statements.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - (Continued)

(unaudited, in millions)

	For the Three Months Ended June 30, 2024
	For the Three Months Ended September 30, 2024
	Preferred stock			Common stock			Additionalpaid-incapital		Accumulatedothercomprehensiveincome (loss)		Retainedearnings		Treasury stock			Totalequity
	Shares	Amount		Shares	Amount								Shares	Amount
Balance, March 31, 2024	—	$	—	169.4	$	0.1	$	329.5	$	(160.5)	$	18,021.0	(23.8)	$	(2,977.1)	$	15,213.0
Net income	—	—		—	—		—		—		583.6		—	—		583.6
Other comprehensive income (loss), net of tax	—	—		—	—		—		14.5		—		—	—		14.5
Issuance of common stock under stock option and stock purchase plans	—	—		0.1	—		7.9		—		—		—	—		7.9
Issuance of common stock under stock award plan	—	—		—	—		(1.8)		—		—		—	—		(1.8)
Compensation related to share-based payments	—	—		—	—		72.9		—		—		—	—		72.9
Other	—	—		—	—		(1.0)		—		—		—	—		(1.0)
Balance, June 30, 2024	—	$	—	169.5	$	0.1	$	407.5	$	(146.0)	$	18,604.6	(23.8)	$	(2,977.1)	$	15,889.1
	For the Six Months Ended June 30, 2024
Net income	—	—		—	—		—		—		388.5		—	—		388.5
Other comprehensive income (loss), net of tax	—	—		—	—		—		0.3		—		—	—		0.3
Issuance of common stock under stock option and stock purchase plans	—	—		—	—		7.6		—		—		—	—		7.6
Issuance of common stock under stock award plan	—	—		—	—		(1.6)		—		—		—	—		(1.6)
Compensation related to share-based payments	—	—		—	—		75.0		—		—		—	—		75.0
Other	—	—		—	—		—		—		—		—	—		—
Balance, September 30, 2024	—	$	—	169.5	$	0.1	$	488.5	$	(145.7)	$	18,993.1	(23.8)	$	(2,977.1)	$	16,358.9
	For the Nine Months Ended September 30, 2024
	Preferred stock			Common stock			Additionalpaid-incapital		Accumulatedothercomprehensiveincome (loss)		Retainedearnings		Treasury stock			TotalBiogen Inc.shareholders’equity
	Shares	Amount		Shares	Amount								Shares	Amount
Balance, December 31, 2023	—	$	—	168.7	$	0.1	$	302.5	$	(153.7)	$	17,627.6	(23.8)	$	(2,977.1)	$	14,799.4
Net income	—	—		—	—		—		—		~~977~~1,365.05		—	—		~~977~~1,365.05
Other comprehensive income (loss), net of tax	—	—		—	—		—		78.70		—		—	—		78.70
Issuance of common stock under stock option and stock purchase plans	—	—		0.2	—		2331.62		—		—		—	—		2331.62
Issuance of common stock under stock award plan	—	—		0.6	—		(6466.40)		—		—		—	—		(6466.40)
Compensation related to share-based payments	—	—		—	—		~~149~~224.0		—		—		—	—		~~149~~224.0
Other	—	—		—	—		(3.2)		—		—		—	—		(3.2)
Balance, June 30, 2024	—	$	—	169.5	$	0.1	$	407.5	$	(146.0)	$	18,604.6	(23.8)	$	(2,977.1)	$	15,889.1
Balance, September 30, 2024	—	$	—	169.5	$	0.1	$	488.5	$	(145.7)	$	18,993.1	(23.8)	$	(2,977.1)	$	16,358.9

See accompanying notes to these unaudited condensed consolidated financial statements.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited)


Note 1:			Summary of Significant Accounting Policies

References in these notes to "Biogen," the "company," "we," "us" and "our" refer to Biogen Inc. and its consolidated subsidiaries.

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 TECFIDERA, VUMERITY, AVONEX, PLEGRIDY and TYSABRI 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 ~~Sage~~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, ~~and~~ 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; FLIXABI, an infliximab biosimilar referencing REMICADE; and BYOOVIZ, a ranibizumab biosimilar referencing LUCENTIS, in certain international markets. We also have commercialization rights related to OPUVIZ, an aflibercept biosimilar referencing EYLEA, in certain international markets.

For additional information on our collaboration arrangements, please read Note 19, Collaborative and Other Relationships, to these unaudited condensed consolidated financial statements (condensed consolidated financial statements).

Basis of Presentation

In the opinion of management, our condensed consolidated financial statements include all adjustments, consisting of normal recurring accruals, necessary for a fair statement of our financial statements for interim periods in accordance with U.S. GAAP. The information included in this quarterly report on Form 10-Q should be read in conjunction with our audited consolidated financial statements and the accompanying notes included in our 2024 Form 10-K. Our accounting policies are described in the Notes to Consolidated Financial Statements in our 2024 Form 10-K and updated, as necessary, in this report. The year-end condensed consolidated balance sheet data presented for comparative purposes was derived from our audited financial statements, but does not include all disclosures required by U.S. GAAP. The results of operations for the three and ~~six~~nine months ended ~~June~~September 30, 2025, are not necessarily indicative of the operating results for the full year or for any other subsequent interim period.

We operate as one operating segment, focused on discovering, developing and delivering innovative therapies for people living with serious and complex diseases.

During the first quarter of 2025 we began presenting acquired in-process research and development, upfront and milestone expense as a separate line item in our condensed consolidated statements of income. Acquired in-process research and development, upfront and milestone expense includes costs incurred in connection with collaboration and license agreements such as upfront and milestone payments and, when applicable, premiums on equity securities and asset acquisitions of acquired in-process research and development, which were previously ~~included in research and development expense. Prior periods have been reclassified to conform to the current period~~

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

included in research and development expense. Prior periods have been reclassified to conform to the current period presentation. The reclassification had no impact on our total cost and expense, net income attributable to Biogen Inc., earnings per share or total equity.

Consolidation

Our condensed consolidated financial statements reflect our financial statements, those of our wholly-owned subsidiaries and variable interest entities where we are the primary beneficiary. For consolidated entities where we own or are exposed to less than 100.0% of the economics, we record net income (loss) attributable to noncontrolling interests, net of tax in our condensed consolidated statements of income equal to the percentage of the economic or ownership interest retained in such entities by the respective noncontrolling parties. Intercompany balances and transactions are eliminated in consolidation.

In determining whether we are the primary beneficiary of a variable interest entity, we apply a qualitative approach that determines whether we have both (1) the power to direct the economically significant activities of the entity and (2) the obligation to absorb losses of, or the right to receive benefits from, the entity that could potentially be significant to that entity. We continuously assess whether we are the primary beneficiary of a variable interest entity as changes to existing relationships or future transactions may result in us consolidating or deconsolidating one or more of our collaborators or partners.

Use of Estimates

The preparation of our condensed consolidated financial statements requires us to make estimates, judgments and assumptions that may affect the reported amounts of assets, liabilities, equity, revenue and expense and related disclosure of contingent assets and liabilities. On an ongoing basis we evaluate our estimates, judgments and assumptions. We base our estimates on historical experience and on various other assumptions that we believe are reasonable, the results of which form the basis for making judgments about the carrying values of assets, liabilities and equity and the amount of revenue and expense. Actual results may differ from these estimates.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Significant Accounting Policies

There have been no material changes to our significant accounting policies disclosed in Note 1, Summary of Significant Accounting Policies, to our audited consolidated financial statements included in our 2024 Form 10-K.

New Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that we adopt as of the specified effective date. Unless otherwise discussed below, we do not believe that the adoption of recently issued standards have had, or may have, a material impact on our condensed consolidated financial statements or disclosures.

Standard

Description

Effective Date

Effects on the financial statements

ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures

This standard establishes incremental disaggregation of income tax disclosures pertaining to the effective tax rate reconciliation and income taxes paid. The amendments in this update are required to be applied on a prospective basis with the option to apply it retrospectively.

Annual reporting for fiscal years beginning after December 15, 2024. Early adoption is permitted.

We are currently evaluating the potential impact that this new standard will have on our consolidated financial statements and related disclosures, and expect to apply this standard prospectively upon adoption.

ASU No. 2024-03, Income Statement (Subtopic 220-40): Reporting Comprehensive Income - Expense Disaggregation Disclosures

This standard requires disclosure in the notes to the financial statements, at each interim and annual reporting period, of specified information about certain costs and expense including purchases of inventory, employee compensation, depreciation and intangible asset amortization included in each relevant expense caption. This standard also requires a qualitative description of the amounts remaining in relevant expense captions that are not separately disaggregated, as well as disclosure of the total amount of selling expenses, and, in annual reporting periods, an entity’s definition of selling expenses.

Annual reporting for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted.

We are currently evaluating the potential impact that this new standard will have on our consolidated financial statements and related disclosures.

ASU No. 2025-07, Derivatives and Hedging (Topic 815) and Revenue from Contracts with Customers (Topic 606): Derivatives Scope Refinements and Scope Clarification for Share-Based Noncash Consideration from a Customer in a Revenue Contract

This standard refines and expands the existing scope exceptions that exclude certain contracts, including certain R&D funding arrangements, from derivative accounting, and clarifies the accounting for share-based noncash consideration received from a customer.

Annual reporting for fiscal years beginning after December 15, 2026, and interim periods within those annual reporting periods. Early adoption is permitted.

We have early adopted this new standard on a modified retrospective basis as of January 1, 2025. Adoption did not have a material impact on our condensed consolidated financial statements and related disclosures.

1516

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)


Note 2:			Acquisitions

Alcyone Therapeutics, Inc.

In September 2025 we entered into a definitive agreement to acquire 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, which is designed to provide an alternative to repeat lumbar punctures in chronic intrathecal administration of medicines.

We have agreed to pay an upfront cash payment of $85.0 million upon closing, plus additional potential amounts payable upon the achievement of certain milestones related to the development and regulatory approval of ThecaFlex DRx for administering SPINRAZA and additional pipeline products.

We plan to account for this proposed acquisition as an asset acquisition as the value being acquired primarily relates to a single asset and plan to record the upfront payment within acquired in-process research and development, upfront and milestone expense within our condensed consolidated statements of income upon the completion of this proposed acquisition. We anticipate the proposed acquisition to close during the fourth quarter of 2025, subject to the satisfaction of customary closing conditions. Under the terms of this proposed acquisition, we expect to oversee the end-to-end development, manufacturing and commercialization of ThecaFlex DRx.

Alcyone's remaining therapeutic assets would be divested from Alcyone into Neela Therapeutics, Inc., a newly formed independent company, prior to the closing of this proposed acquisition. We anticipate to make a convertible debt investment of up to $5.0 million in Neela Therapeutics. Inc.

Human Immunology Biosciences

On July 2, 2024, we completed the acquisition of all of the issued and outstanding shares of HI-Bio, a privately-held clinical-stage biotechnology company focused on targeted therapies for patients with severe immune-mediated diseases. HI-Bio's lead asset, felzartamab, an anti-CD38 antibody, is currently being evaluated for several indications, including three leading indications, AMR, PMN and IgAN. Felzartamab has received Breakthrough Therapy Designation and ODD from the FDA for development in the treatment of PMN and AMR. Subsequent to our acquisition, felzartamab received ODD in the E.U. in IgAN and solid organ transplantation. The acquisition of HI-Bio is expected to augment our pipeline and build on our expertise in immunology.

Under the terms of this acquisition, we paid shareholders of HI-Bio approximately $1.15 billion at closing and may pay up to ana ~~additional~~total of $650.0 million in contingent development and regulatory milestone payments. The $1.15 billion paid includes approximately $74.5 million related to HI-Bio's outstanding, non-vested equity awards, inclusive of employer taxes, of which $56.4 million was recognized as share-based compensation payments to settle non-vested equity awards attributable to the post-acquisition service period and therefore not reflected as a component of total purchase price paid. Of the total $56.4 million, we recognized approximately $42.5 million as a charge to research and development expense with the remaining $13.9 million as a charge to selling, general and administrative expense within our condensed consolidated statements of income for the ~~year~~three ~~ended~~and ~~December~~nine ~~31,~~months ~~2024,~~ended ~~included~~September in30, ~~our 2024 Form 10-K~~2025. These amounts were associated with the accelerated vesting of stock options and RSUs previously granted to HI-Bio employees and required no future services to vest.

Upon closing we also paid an additional $43.7 million related to working capital adjustments as of the transaction close date, which was included as a component of total purchase price paid.

We funded this acquisition through available cash on hand and accounted for this acquisition as a business combination using the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations, and recorded assets acquired and liabilities assumed at their respective fair values as of the acquisition date.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Purchase Price Consideration

Total consideration transferred for the acquisition of HI-Bio is summarized as follows:


(In millions)	As of July 2, 2024
Cash consideration paid to HI-Bio shareholders(1)	$	1,137.3
Contingent consideration	485.1

Total consideration	$	1,622.4

(1) Represents total consideration paid to shareholders of HI-Bio of $1.15 billion, plus an additional $43.7 million related to working capital adjustments as of the transaction close date, less $56.4 million of cash paid for HI-Bio's outstanding, non-vested equity awards, inclusive of employer taxes, which were recognized as compensation attributable to the post-acquisition service period and therefore not reflected as a component of total consideration.

Contingent Consideration: We may make certain contingent payments to the former shareholders of HI-Bio upon the achievement of certain development and regulatory milestones. As of the acquisition date, the maximum aggregate amount payable for these potential milestones was $650.0 million. The acquisition-date fair value of these milestones was approximately $485.1 million and was estimated utilizing a probability-adjusted discounted cash flow calculation using an appropriate discount rate dependent on the nature and timing of the milestone payments, which ranged from 6.2% to 7.0%, and probabilities of technological and regulatory success ranging from 67.0% to near-certain probability. Of the total contingent consideration, approximately $279.3 million related to milestones classified as short-term and reflected as a component of accrued expense and other with the remaining $205.8 million reflected as a component of other long-term liabilities within our condensed consolidated balance sheets. The short-term liability related to the fourth patient dosed in a Phase 3 clinical trial of felzartamab in a first and second indication, which would each result in the achievement of a $150.0 million milestone payment. During the second quarter of 2025 the first milestone related to the fourth patient dosed in a phase 3 clinical trial of felzartamab for AMR was achieved, resulting in a $150.0 million milestone payment made to the former shareholders of HI-Bio, which was substantially paid in July 2025.

16Of the total contingent consideration, approximately $279.3 million related to milestones classified as short-term and reflected as a component of accrued expense and other with the remaining $205.8 million reflected as a component of other long-term liabilities within our condensed consolidated balance sheets. The short-term liability related to the fourth patient dosed in a Phase 3 clinical trial of felzartamab in a first and second indication, which would each result in the achievement of a $150.0 million milestone payment. During the second quarter of 2025 the first milestone related to the fourth patient dosed in a phase 3 clinical trial of felzartamab for AMR was achieved, resulting in a $150.0 million milestone payment made to the former shareholders of HI-Bio, which was paid during the third quarter of 2025. In October 2025 the second milestone related to the fourth patient dosed in a phase 3 clinical trial of felzartamab for IgAN was achieved, resulting in a $150.0 million milestone payment to be made to the former shareholders of HI-Bio, which we expect will be paid during the fourth quarter of 2025.

Subsequent changes in the fair value of the contingent consideration obligation are being recognized as (gain) loss on fair value remeasurement of contingent consideration within our condensed consolidated statements of income. This fair value measurement is based on significant inputs that are not observable in the market and thus represent Level 3 fair value measurements. For additional information related to the fair value of this obligation, please read Note 8, Fair Value Measurements, to these condensed consolidated financial statements.

Other Contractual Commitments: We acquired HI-Bio's pre-existing in-license commitments under third-party agreements with MorphoSys, which included tiered royalties on potential future sales ranging from high-single digit to mid-teen percentages, as well as potential development, regulatory and commercial milestone payments of up to $130.0 million, $230.0 million and $640.0 million, respectively. At the transaction close date the achievement of these milestones was not considered probable and therefore not recorded in our financial statements.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Purchase Price Allocation

We finalized purchase accounting for this acquisition in the second quarter of 2025.

The following table summarizes the amounts recognized for assets acquired and liabilities assumed as of the acquisition date, and reflects measurement period adjustments made to the amounts initially recorded as of the acquisition date on July 2, 2024. The related impact to our condensed consolidated statements of income that would have been recognized in previous periods if the adjustments were recognized as of the acquisition date is immaterial.

(In millions)	Amounts Recognized as of Acquisition Date(as adjusted)~~June 30, 2025~~
Cash and cash equivalents	$	62.5
Intangible assets:
IPR&D - felzartamab (IgAN)	920.0
IPR&D - felzartamab (AMR)	450.0
IPR&D - felzartamab (PMN)	265.0
Other clinical programs	7.9
Prepaid expense and other assets(1)	1.4
Operating lease assets	1.2
Accounts payable	(1.1)
Accrued liabilities	(35.0)
Deferred tax liability(1)	(309.3)
Operating lease liabilities	(1.2)
Total identifiable net assets	1,361.4
Goodwill(1)	261.0
Total assets acquired and liabilities assumed	$	1,622.4

(1) Includes measurement period adjustments recorded in 2025 that increased prepaid expense and other assets by $0.4 million, net deferred tax liability by $4.9 million and goodwill by $4.5 million.

Intangible assets: Intangible assets comprised of approximately $1.6 billion of IPR&D related to HI-Bio's lead asset felzartamab. This includes $920.0 million of IPR&D related to felzartamab indication for IgAN, $450.0 million of IPR&D related to felzartamab indication for AMR and $265.0 million of IPR&D related to felzartamab indication for PMN. The estimated fair values of the program related intangible assets were determined using a multi-period excess earnings method, a form of the income approach, utilizing cash flow analyses and a discount rate of 14.5%. These fair value measurements were based on significant inputs that are not observable in the market and thus represent Level 3 fair value measurements.

17Goodwill: Goodwill was calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from the other assets acquired that could not be individually identified and separately recognized. We recognized goodwill of approximately $261.0 million, which includes measurement period adjustments, and is not deductible for tax purposes. The goodwill recognized from our acquisition of HI-Bio is primarily the result of the deferred tax consequences from the transaction recorded for financial statement purposes.

Acquisition-related expense: Acquisition-related expense, primarily comprised of advisory and legal fees, and other transaction costs, totaled approximately $2.8 million and were recorded within selling, general and administrative expense within our consolidated statements of income for the year ended December 31, 2024, included in our 2024 Form 10-K.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Goodwill: Goodwill was calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from the other assets acquired that could not be individually identified and separately recognized. We recognized goodwill of approximately $261.0 million, which includes measurement period adjustments, and is not deductible for tax purposes. The goodwill recognized from our acquisition of HI-Bio is primarily the result of the deferred tax consequences from the transaction recorded for financial statement purposes.


Note 3:			Dispositions

Sale of Joint Venture Equity Interest in Samsung Bioepis

In April 2022 we completed the sale of our 49.9% equity interest in Samsung Bioepis to Samsung BioLogics in exchange for total consideration of approximately $2.3 billion. Under the terms of this transaction, we received approximately $1.0 billion in cash at closing, with approximately $1.3 billion in cash to be deferred over two payments. The first deferred payment of $812.5 million was received in April 2023 and the second deferred payment of $437.5 million was received in April 2024.

For the ~~three~~nine ~~and six~~ months ended ~~June~~September 30, 2024, we recognized ~~gains~~a gain of approximately $~~1.4 million and $~~7.5 million, ~~respectively,~~ to reflect the ~~changes~~change in fair value associated with the passage of time related to the second deferred payment due to us, which was received in April 2024 and recorded in other (income) expense, net within our condensed consolidated statements of income.

For additional information on the sale of our equity interest in Samsung Bioepis, please read Note 3, Dispositions, to our consolidated financial statements included in our 2024 Form 10-K.

Sale of Priority Review Voucher

In April 2024 we completed the sale of our rare pediatric disease PRV, generated by the development associated with SPINRAZA, to a third party. In consideration for the PRV we received a cash payment of $103.0 million upon the closing of the PRV purchase, of which approximately $14.4 million was paid to Ionis. Our net portion of approximately $88.6 million was recognized in gain on sale of priority review voucher, net within our condensed consolidated statements of income for the ~~three~~nine ~~and six~~ months ended ~~June~~September 30, 2024.

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 and recognized a de minimis loss within our condensed consolidated statements of income for the ~~six~~nine months ended ~~June~~September 30, 2025.


Note 4:			Restructuring

2023 Fit for Growth Restructuring Program

In 2023 we initiated cost saving measures as part of our Fit for Growth program to reduce operating costs, while improving operating efficiency and effectiveness. The Fit for Growth program is expected to generate approximately $1.0 billion in gross operating expense savings by the end of 2025, some of which will be reinvested in various initiatives. The Fit for Growth program is currently estimated to include net headcount reductions of approximately 1,400 employees and we expect to incur total restructuring charges ~~ranging~~of ~~from~~ approximately $~~300.0 million to $~~310.0 million~~. As of June 30~~, ~~2025,~~which ~~cumulative~~were ~~total~~substantially ~~restructuring~~achieved ~~charges~~as ~~incurred~~of inSeptember ~~connection~~30, ~~with our Fit for Growth program totaled approximately $300~~2025.~~0 million.~~

1820

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Total charges incurred from our 2023 Fit for Growth program are summarized as follows:

	For the Three Months Ended June 30,
	For the Three Months Ended September 30,
	2025						2024
(In millions)	SeveranceCosts		Accelerated Depreciation and Other Costs		Total		Severance Costs		Accumulated Depreciation and Other Costs		Total
Selling, general and administrative	$	—	$	0.74	$	0.74	$	—	$	29.01	$	29.01
Research and development	—		10.35		10.35		—		23.25		23.25
Restructuring charges	(17.1)4		—		(17.1)4		64.36		—		64.36
Total charges	$	(17.1)4	$	2.0.9	$	08.93	$	64.36	$	412.26	$	1017.52
	For the Six Months Ended June 30,
	For the Nine Months Ended September 30,
	2025						2024
(In millions)	Severance Costs		Accelerated Depreciation and Other Costs		Total		Severance Costs		Accumulated Depreciation and Other Costs		Total
Selling, general and administrative	$	—	$	(3.2.8)	$	(3.2.8)	$	—	$	312.45	$	312.45
Research and development	—		6.49		6.49		—		710.16		710.16
Restructuring charges	3441.26		—		3441.26		1520.62		—		1520.62
Total charges	$	3441.26	$	34.21	$	3745.47	$	1520.62	$	1023.51	$	2643.13

Other Costs: Includes costs associated with items such as asset abandonment and write-offs, facility closure costs, pre-tax gains and losses resulting from the termination of certain leases, employee non-severance expense, consulting fees and other costs.

Reata Integration

Following the close of our Reata acquisition in September 2023, we implemented an integration plan designed to realize operating synergies through cost savings and avoidance. Under this initiative, we ~~estimate~~estimated we ~~will~~would incur total integration charges of approximately $35.0 million related to severance and employment costs., ~~These~~which ~~severance and employment costs~~ were substantially incurred during 2023.

Total charges incurred from our Reata integration are summarized as follows:

	For the Three Months Ended June 30,
	For the Three Months Ended September 30,
	2025						2024
(In millions)	SeveranceCosts		Accelerated Depreciation and Other Costs		Total		Severance Costs		Accumulated Depreciation and Other Costs		Total
Selling, general and administrative	$	—	$	1.86	$	1.86	$	—	$	1.56	$	1.56
Research and development	—		43.08		43.08		—		32.39		32.39
Restructuring charges	—		—		—		0.37		—		0.37
Total charges	$	—	$	5.84	$	5.84	$	0.37	$	4.85	$	5.12
	For the Six Months Ended June 30,
	For the Nine Months Ended September 30,
	2025						2024
(In millions)	Severance Costs		Accelerated Depreciation and Other Costs		Total		Severance Costs		Accumulated Depreciation and Other Costs		Total
Selling, general and administrative	$	—	$	35.62	$	35.62	$	—	$	34.39	$	34.39
Research and development	—		610.31		610.31		—		68.09		68.09
Restructuring charges	(0.2)		—		(0.2)		23.52		—		23.52
Total charges	$	(0.2)	$	915.93	$	915.71	$	23.52	$	913.38	$	1117.80

1921

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

In connection with our acquisition of Reata we assumed responsibility for a single-tenant, build-to-suit building of approximately 327,400 square feet of office and laboratory space located in Plano, Texas, with an initial lease term of 16 years. We do not intend to occupy this building and are evaluating opportunities to sublease the property. For additional information on our acquisition of Reata, please read Note 2, Acquisitions, to our consolidated financial statements included in our 2024 Form 10-K.

Restructuring Reserve

Charges and spending related to workforce reductions are summarized as follows:

	Workforce Reductions
(In millions)	2025		2024
Restructuring reserve as of January 1	$	31.9		$	75.4
Expense	35.3			11.5
Payment	(25.8)			(42.2)
Foreign currency and other adjustments	(1.0)			0.8
Restructuring reserve as of March 31	40.4			45.5
Expense	(0.7)			6.6
Payment	(9.5)			(11.9)
Foreign currency and other adjustments	(1.0)			—
Restructuring reserve as of June 30	$29.2	~~29.2~~		$40.2	~~40.2~~
Expense	7.4			6.8
Payment	(17.4)			(4.7)
Foreign currency and other adjustments	—			(2.1)
Restructuring reserve as of September 30	$	19.2		$	40.2

2022

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)


Note 5:			Revenue

Product Revenue

Revenue by product is summarized as follows:

	For the Three Months Ended June 30,
	For the Three Months Ended September 30,
	2025						2024
(In millions)	UnitedStates		Rest ofWorld		Total		UnitedStates		Rest ofWorld		Total
Multiple Sclerosis:
TECFIDERA	$	4744.26	$	~~146~~123.46	$	~~193~~168.62	$	4440.1	$	~~208~~192.17	$	~~252~~232.28
VUMERITY	~~188~~189.06		2425.30		~~212~~214.36		~~144~~134.29		2123.62		~~165~~158.81
Total Fumarate	~~235~~234.2		~~170~~148.76		~~405~~382.98		~~188~~175.30		~~229~~215.79		~~418~~390.09
AVONEX	~~121~~133.74		5655.01		~~177~~188.75		~~117~~115.26		6560.6		~~182~~176.82
PLEGRIDY	2827.38		4030.76		6958.04		2827.29		3933.94		6861.13
Total Interferon	~~150~~161.02		9685.7		246.79		~~145~~143.45		~~105~~94.50		~~250~~237.95
TYSABRI	~~272~~247.25		~~182~~184.43		~~454~~431.68		~~248~~227.75		~~213~~178.56		~~462~~406.21
FAMPYRA(1)	—		—		—		—		1819.74		1819.74
Subtotal: Multiple Sclerosis	~~657~~642.49		~~449~~418.86		1,~~107~~061.25		~~582~~546.40		~~567~~507.49		1,~~149~~053.89
Rare Disease:
SPINRAZA	~~149~~153.32		~~243~~220.48		~~392~~374.70		~~157~~153.31		~~271~~228.83		~~429~~381.14
SKYCLARYS(2)	7874.06		5258.3		~~130~~132.39		7581.68		2420.45		~~100~~102.03
QALSODY(3)	7.53		1219.51		2026.04		45.65		05.46		511.01
Subtotal: Rare Disease	~~234~~235.81		~~308~~298.2		~~543~~533.03		~~237~~240.54		~~296~~254.64		~~534~~494.18
Biosimilars:
BENEPALI	—		~~112~~121.19		~~112~~121.19		—		~~117~~118.31		~~117~~118.31
IMRALDI	—		4652.76		4652.76		—		5354.21		5354.21
FLIXABI	—		1415.3		1415.3		—		1316.12		1316.12
BYOOVIZ	2.50		65.10		87.60		104.31		3.49		138.70
TOFIDENCE	—		—		—		0.82		—		0.82
Subtotal: Biosimilars	2.50		~~179~~194.28		~~181~~196.78		114.13		~~187~~192.03		~~198~~196.16
Other:
ZURZUVAE	4655.43		—		4655.43		1422.90		—		1422.90
Other(4)	—		~~0.4~~—		~~0.4~~—		0.83		1.98		2.71
Subtotal: Other	4655.43		~~0.4~~—		4655.83		1522.73		1.98		1724.61
Total product revenue, net	$	~~941~~935.13	$	~~937~~911.6	$	1,~~878~~846.79	$	~~846~~813.70	$	~~1,052~~956.94	$	1,~~899~~769.64

(1) Effective January 1, 2025, our collaboration and license agreement for FAMPYRA global commercialization rights was terminated.

(2) SKYCLARYS became commercially available in the E.U. during the first quarter of 2024.

(3) QALSODY became commercially available in the E.U. during the second quarter of 2024.

(4) Other includes FUMADERM and ADUHELM.

2123

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

	For the Six Months Ended June 30,
	For the Nine Months Ended September 30,
	2025						2024
(In millions)	UnitedStates		Rest ofWorld		Total		UnitedStates		Rest ofWorld		Total
Multiple Sclerosis:
TECFIDERA	$	87131.06	$	~~312~~436.73	$	~~399~~567.79	$	87127.89	$	~~418~~611.74	$	~~506~~739.53
VUMERITY	~~305~~494.17		4671.0		~~351~~565.17		~~250~~385.10		4366.24		~~293~~451.34
Total Fumarate	~~392~~626.13		~~358~~507.73		~~750~~1,133.86		~~337~~512.9		~~461~~677.98		~~799~~1,190.87
AVONEX	~~230~~363.37		~~114~~169.23		~~344~~533.50		~~228~~344.40		~~132~~193.95		~~361~~537.35
PLEGRIDY	5280.42		76106.17		~~128~~186.59		5684.87		76109.48		~~133~~194.25
Total Interferon	~~282~~443.79		~~190~~276.30		~~473~~719.09		~~285~~428.27		~~209~~303.3		~~494~~732.50
TYSABRI	~~473~~720.05		~~363~~547.14		~~836.~~1,267.9		~~462~~690.50		~~431~~609.06		~~893~~1,299.56
FAMPYRA(1)	—		0.3		0.3		—		3757.93		3757.93
Subtotal: Multiple Sclerosis	1,~~147~~790.87		~~912~~1,331.40		23,~~060~~121.27		1,~~085~~631.6		1,~~140~~648.10		23,~~225~~279.76
Rare Disease:
SPINRAZA	~~303~~456.79		~~512~~733.97		~~816~~1,190.6		~~305~~458.89		~~464~~692.69		~~770~~1,151.48
SKYCLARYS(2)	~~147~~221.17		~~107~~165.14		~~254~~387.21		~~148~~230.64		2949.49		~~178~~280.03
QALSODY(3)	1522.03		2039.56		3561.59		914.05		0.6.2		920.67
Subtotal: Rare Disease	~~465~~700.89		~~640~~938.57		1,~~106~~639.36		~~463~~703.48		~~494~~749.60		~~958~~1,452.08
Biosimilars:
BENEPALI	—		~~223~~345.43		~~223~~345.43		—		~~236~~354.01		~~236~~354.01
IMRALDI	—		94146.17		94146.17		—		~~108~~162.01		~~108~~162.01
FLIXABI	—		2742.47		2742.47		—		3047.91		3047.91
BYOOVIZ	68.7		1015.8		1724.5		1418.01		59.32		1927.3
TOFIDENCE	0.1		—		0.1		01.80		—		01.80
Subtotal: Biosimilars	68.8		~~355~~550.75		~~362~~559.53		1419.81		~~380~~572.25		~~395~~591.06
Other:
ZURZUVAE	74129.14		—		74129.14		2749.3		—		2749.3
Other(4)	0.4		1.7		2.1		12.70		35.86		57.56
Subtotal: Other	74129.58		1.7		76131.25		2951.03		35.86		3256.89
Total product revenue, net	$	12,~~694~~630.92	$	12,~~910~~821.39	$	35,~~605~~452.21	$	12,~~592~~405.8	$	2,~~018~~975.71	$	35,~~611~~380.59

(1) Effective January 1, 2025, our collaboration and license agreement for FAMPYRA global commercialization rights was terminated.

(2) SKYCLARYS became commercially available in the E.U. during the first quarter of 2024.

(3) QALSODY became commercially available in the E.U. during the second quarter of 2024.

(4) Other includes FUMADERM and ADUHELM.

We recognized revenue from two wholesalers accounting for 2827.28% and 1516.80% of gross product revenue for the three months ended ~~June~~September 30, 2025, and 27.13% and 15.04% of gross product revenue for the ~~six~~nine months ended ~~June~~September 30, 2025.

We recognized revenue from two wholesalers accounting for 25.49% and 1214.38% of gross product revenue for the three months ended ~~June~~September 30, 2024, and 25.56% and 12.09% of gross product revenue for the ~~six~~nine months ended ~~June~~September 30, 2024.

2224

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

An analysis of the change in reserves for discounts and allowances is summarized as follows:

(In millions)	Discounts		ContractualAdjustments		Returns		Total
Balance, December 31, 2024	$	162.7	$	880.8	$	48.1	$	1,091.6
Current provisions relating to sales in current year	~~394~~607.14		12,~~402~~052.16		1420.97		12,~~811~~680.17
Adjustments relating to prior years	1.48		(6382.70)		31.30		(5979.02)
Payments/credits relating to sales in current year	(~~290~~497.43)		(~~744~~1,271.1)		(0.25)		(1,~~034~~768.79)
Payments/credits relating to sales in prior years	(91111.85)		(~~440~~479.42)		(511.85)		(~~538~~602.02)
Balance, June 30, 2025	$	176.0	$	1,034.7	$	60.3	$	1,271.0
Balance, September 30, 2025	$	163.1	$	1,101.1	$	57.8	$	1,322.0

The total reserves above, which are included in our condensed consolidated balance sheets, are summarized as follows:

(In millions)	As of ~~June~~September 30, 2025		As of December 31, 2024
Reduction of accounts receivable	$	~~273~~259.67	$	154.1
Component of accrued expense and other	~~997~~1,062.43		937.5
Total revenue-related reserves	$	1,~~271~~322.0	$	1,091.6

Revenue from Anti-CD20 Therapeutic Programs

Revenue from anti-CD20 therapeutic programs is summarized in the table below. For the purposes of this footnote, we refer to RITUXAN and RITUXAN HYCELA collectively as RITUXAN.

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Royalty revenue on sales of OCREVUS	$	~~353~~386.84	$	~~336~~346.38	$	~~642~~1,029.60	$	~~639~~985.08
Biogen’s share of pre-tax profits in the U.S. for RITUXAN, GAZYVA and LUNSUMIO	~~107~~101.70		~~103~~94.48		~~191~~292.4		~~190~~285.53
Other revenue from anti-CD20 therapeutic programs	56.85		4.86		1118.50		913.06
Total revenue from anti-CD20 therapeutic programs	$	~~467~~493.39	$	~~444~~446.52	$	~~845~~1,339.54	$	~~838~~1,284.57

For additional information on our collaboration arrangements with Genentech, please read Note 19, Collaborative and Other Relationships, to these condensed consolidated financial statements.

Alzheimer's Collaboration Revenue

Alzheimer's collaboration revenue consists of our 50.0% share of LEQEMBI product revenue, net and cost of sales, including royalties, as we are not the principal. We began recognizing Alzheimer's collaboration revenue upon the accelerated approval of LEQEMBI in the U.S. during the first quarter of 2023.

For the three and ~~six~~nine months ended ~~June~~September 30, 2025, we recognized Alzheimer's collaboration revenue of approximately $5442.97 million and $87130.96 million, respectively, compared to $1118.86 million and $1433.62 million, respectively, in the prior year comparative periods.

For additional information on our collaboration arrangements with Eisai, please read Note 19, Collaborative and Other Relationships, to these condensed consolidated financial statements.

2325

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Contract Manufacturing, Royalty and Other Revenue

Contract manufacturing, royalty and other revenue is summarized as follows:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Contract manufacturing revenue	$	~~225~~141.05	$	~~100~~221.09	$	~~507~~648.38	$	~~252~~474.21
Royalty and other revenue	199.67		9.07		3040.63		3848.63
Total contract manufacturing, royalty and other revenue	$	~~244~~151.62	$	~~109~~231.06	$	~~537~~689.91	$	~~290~~522.84

Contract Manufacturing Revenue

Contract manufacturing revenue primarily reflects amounts earned under contract manufacturing agreements with our strategic customers and batches of LEQEMBI related to our collaboration with Eisai.

Royalty and Other Revenue

Royalty and other revenue primarily reflects royalty revenue on biosimilar products from our license arrangements with Samsung Bioepis and royalties we receive from net sales on products related to patents that we have out-licensed.

For additional information on our license arrangements with Samsung Bioepis and our collaboration arrangements with Eisai, please read Note 19, Collaborative and Other Relationships, to these condensed consolidated financial statements.


Note 6:			Inventory

The components of inventory are summarized as follows:

(In millions)	As of ~~June~~September 30, 2025		As of December 31, 2024
Raw materials	$	~~305~~296.02	$	317.8
Work in process	1,~~641~~635.90		1,882.8
Finished goods	~~478~~440.05		353.8
Total inventory	$	2,~~424~~371.97	$	2,554.4
Balance Sheet Classification:
Inventory	$	2,~~274~~209.34	$	2,460.5
Investments and other assets	~~150~~162.63		93.9
Total inventory	$	2,~~424~~371.97	$	2,554.4

Long-term inventory is included in investments and other assets within our condensed consolidated balance sheets.

As a result of our acquisition of Reata in September 2023 we recorded a fair value step-up adjustment related to the acquired inventory of SKYCLARYS of approximately $1.3 billion. This fair value step-up adjustment is being amortized to cost of sales within our condensed consolidated statements of income as the inventory is sold or used for clinical purposes. We expect this amount to be fully amortized by the end of 2028. For the three and ~~six~~nine months ended ~~June~~September 30, 2025, amortization from the fair value step-up adjustment was approximately $5261.5 million and $~~103~~165.94 million, respectively. For the three and ~~six~~nine months ended ~~June~~September 30, 2024, amortization from the fair value step-up adjustment was approximately $9050.19 million and $~~134~~185.21 million, respectively, which includes approximately $462.05 million and $48.5 million, respectively, of inventory used for clinical purposes, which is reflected in research and development expense within our condensed consolidated statements of income. For additional information on our acquisition of Reata, please read Note 2, Acquisitions, to our consolidated financial statements included in our 2024 Form 10-K.

2426

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)


Note 7:			Intangible Assets and Goodwill

Intangible Assets

Intangible assets, net of accumulated amortization, impairment charges and adjustments are summarized as follows:

		As of June 30, 2025						As of December 31, 2024
		As of September 30, 2025						As of December 31, 2024
(In millions)	Estimated Life	Cost		AccumulatedAmortization		Net		Cost		AccumulatedAmortization		Net
Completed technology	2-31 years	$	14,087.12	$	(6,~~423~~558.07)	$	7,~~664~~528.15	$	14,138.4	$	(6,254.1)	$	7,884.3
In-process research and development	Indefinite until commercialization	1,639.4		—		1,639.4		1,642.9		—		1,642.9
Priority review voucher	Indefinite	100.0		—		100.0		100.0		—		100.0
Trademarks and trade names	Indefinite	64.0		—		64.0		64.0		—		64.0
Total intangible assets		$	15,890.56	$	(6,~~423~~558.07)	$	9,~~467~~331.59	$	15,945.3	$	(6,254.1)	$	9,691.2

Amortization and Impairments

For the three and ~~six~~nine months ended ~~June~~September 30, 2025, amortization and impairment of acquired intangible assets totaled $~~130~~135.97 million and $~~242~~378.74 million, respectively, compared to $86130.93 million and $~~165~~295.25 million, respectively, in the prior year comparative periods.

For the three and ~~six~~nine months ended ~~June~~September 30, 2025, amortization of acquired intangible assets, excluding impairment charges, totaled $~~127~~135.47 million and $~~239~~374.29 million, respectively, compared to $86110.91 million and $~~165~~275.23 million, respectively, in the prior year comparative periods. The increases were primarily due to amortization for the acquired intangible assets associated with SKYCLARYS and TYSABRI.

For the three ~~and~~months ~~six~~ended September 30, 2025, we had no impairment charges. For the nine months ended ~~June~~September 30, 2025, amortization and impairment of acquired intangible assets reflects the impact of a $3.5 million impairment charge related to a compound acquired from HI-Bio. For the three and ~~six~~nine months ended ~~June~~September 30, 2024, weamortization ~~had~~and noimpairment of acquired intangible assets reflects impairment charges of approximately $20.2 million related to intangible assets associated with the termination of Samsung Bioepis' commercialization rights during the third quarter of 2024.

Completed Technology

Completed technology primarily relates to our other marketed products and programs acquired through asset acquisitions, licenses and business combinations. Completed technology intangible assets are amortized over their estimated useful lives, which range between 2 to 31 years, with a remaining weighted average useful life of 12 years.

IPR&D Related to Business Combinations

IPR&D represents the fair value assigned to research and development assets that we acquired as part of a business combination and had not yet reached technological feasibility at the date of acquisition. Included in IPR&D balances are adjustments related to foreign currency exchange rate fluctuations.

The carrying value associated with our IPR&D assets as of ~~June~~September 30, 2025 and December 31, 2024, primarily relates to the IPR&D programs we acquired in connection with our acquisition of HI-Bio in July 2024, with an estimated fair value of approximately $1.6 billion.

Priority Review Voucher

In connection with our acquisition of Reata in September 2023 we acquired a rare pediatric disease PRV which may be used to obtain priority review by the FDA for a future regulatory submission or sold to a third party. We recorded the PRV based on its estimated fair value of $100.0 million as an intangible asset.

2527

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Estimated Future Amortization of Intangible Assets

The estimated future amortization of finite-lived intangible assets for the next five years is expected to be as follows:

(In millions)	As of ~~June~~September 30, 2025
2025 (remaining six months)	$	240.0
2025 (remaining three months)	$	130.0
2026	~~565~~485.0
2027	~~600~~490.0
2028	~~630~~525.0
2029	~~665~~580.0
2030	~~700~~650.0

Goodwill

The following table provides a roll forward of the changes in our goodwill balance:

(In millions)	As of ~~June~~September 30, 2025
Goodwill, December 31, 2024	$	6,478.9
Goodwill resulting from HI-Bio acquisition(1)	4.5
Other(2)	9.7.3
Goodwill, June 30, 2025	$	6,493.1
Goodwill, September 30, 2025	$	6,490.7

(1) Goodwill resulting from the HI-Bio acquisition relates to HI-Bio measurement period adjustments recognized during 2025 related to certain income tax adjustments. For additional information on our acquisition of HI-Bio, please read Note 2, Acquisitions, to these condensed consolidated financial statements.

(2) Other includes adjustments related to foreign currency exchange rate fluctuations.

As of ~~June~~September 30, 2025, we had no impairment losses related to goodwill.

2628

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)


Note 8:			Fair Value Measurements

The tables below present information about our assets and liabilities that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques we utilized to determine such fair value:

	Fair Value Measurements on a Recurring Basis
	As of June 30, 2025
	As of September 30, 2025
(In millions)	Total		Quoted Pricesin ActiveMarkets(Level 1)		SignificantOther ObservableInputs(Level 2)		SignificantUnobservableInputs(Level 3)
Assets:
Cash equivalents	$	23,~~234~~398.98	$	—	$	23,~~234~~398.98	$	—
Marketable equity securities	157.0		157.0		—		—
Marketable debt securities:
Corporate debt securities	71.0		—		71.0		—
Government securities	26.6		—		26.6		—
Marketable equity securities	103.9		103.9		—		—
Other current assets:
Derivative contracts	319.76		—		319.76		—
Other non-current assets:
Convertible note(1)	30.0		—		—		30.0
Plan assets for deferred compensation	5051.18		—		5051.18		—
Total	$	23,~~503~~691.7	$	~~157~~103.09	$	23,~~316~~557.78	$	30.0
Liabilities:
Other current liabilities:
Derivative contracts	$	~~123~~89.71	$	—	$	~~123~~89.71	$	—
Contingent consideration obligations	~~297~~148.26		—		—		~~297~~148.26
Other non-current liabilities:
Derivative contracts	2610.82		—		2610.82		—
Contingent consideration obligations	~~237~~242.76		—		—		~~237~~242.76
Total	$	~~685~~490.45	$	—	$	~~150~~99.53	$	~~534~~391.92

(1) As part of our strategic research arrangement with City Therapeutics we invested in a convertible note, for which we elected the fair value option. For additional information on the arrangement with City Therapeutics, please read Note 19, Collaborative and Other Relationships, to these condensed consolidated financial statements.


	Fair Value Measurements on a Recurring Basis
	As of December 31, 2024
(In millions)	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	1,664.9	$	—	$	1,664.9	$	—




Marketable equity securities	179.7		179.7		—		—
Other current assets:
Derivative contracts	62.5		—		62.5		—
Other non-current assets:

Plan assets for deferred compensation	42.8		—		42.8		—
Total	$	1,949.9	$	179.7	$	1,770.2	$	—
Liabilities:
Other current liabilities:
Derivative contracts	$	11.7	$	—	$	11.7	$	—
Contingent consideration obligations	291.2		—		—		291.2
Other non-current liabilities:

Contingent consideration obligations	221.6		—		—		221.6
Total	$	524.5	$	—	$	11.7	$	512.8

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

	Fair Value Measurements on a Recurring Basis
	As of December 31, 2024
(In millions)	Total		Quoted Pricesin ActiveMarkets(Level 1)		SignificantOther ObservableInputs(Level 2)		SignificantUnobservableInputs(Level 3)
Assets:
Cash equivalents	$	1,664.9	$	—	$	1,664.9	$	—
Marketable equity securities	179.7		179.7		—		—
Other current assets:
Derivative contracts	62.5		—		62.5		—
Other non-current assets:
Plan assets for deferred compensation	42.8		—		42.8		—
Total	$	1,949.9	$	179.7	$	1,770.2	$	—
Liabilities:
Other current liabilities:
Derivative contracts	$	11.7	$	—	$	11.7	$	—
Contingent consideration obligations	291.2		—		—		291.2
Other non-current liabilities:
Contingent consideration obligations	221.6		—		—		221.6
Total	$	524.5	$	—	$	11.7	$	512.8

Our marketable equity securities represent investments in publicly traded equity securities. Our ability to liquidate our investment in Denali may be limited by the size of our interest, the volume of market-related activity, our concentrated level of ownership and potential restrictions resulting from our status as a collaborator. Therefore, we may realize significantly less than the current value of such investments.

In ~~June~~July 2025 Sage ~~announced~~was itacquired ~~entered~~by ~~into~~Supernus. aPrior ~~definitive~~to ~~agreement~~this ~~for Supernus Pharmaceuticals~~acquisition, ~~Inc.~~we todisposed ~~acquire~~of ~~Sage,~~all ~~with~~of ~~the~~our ~~transaction~~shares ~~expected~~of toSage ~~close~~common stock in ~~the~~a ~~third~~block ~~quarter of 2025~~trade.

As set forth in the amended Schedule 13D we filed with the SEC on July 30, 2025, we have disposed of all of our shares of Sage common stock in a block trade.

For additional information on our investments in Denali and Sage common stock, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in our 2024 Form 10-K.

There have been no material impairments of our assets measured and carried at fair value as of ~~June~~September 30, 2025 and December 31, 2024. In addition, there have been no changes to our valuation techniques as of ~~June~~September 30, 2025 and December 31, 2024.

For a description of our validation procedures related to prices provided by third-party pricing services and our option pricing valuation model, please read Note 1, Summary of Significant Accounting Policies - Fair Value Measurements, to our consolidated financial statements included in our 2024 Form 10-K.

Level 3 Assets and Liabilities Held at Fair Value

The following ~~table~~tables ~~presents~~present quantitative information, as of the dates indicated, about the valuation techniques and significant unobservable inputs used in the valuation of our Level 3 financial assets and liabilities measured at fair value on a recurring basis:

Quantitative Information about Level 3 Fair Value Measurements

As of September 30, 2025

(In millions)

Fair Value

Valuation Technique

Significant
Unobservable Input(s)

Range

Weighted Average

Liabilities:

Contingent consideration obligations

391.2

Discounted cash flow

Discount rate

5.4% - 5.5%

5.4

Expected timing of achievement of development milestones

2025 - 2030

—

Quantitative Information about Level 3 Fair Value Measurements

As of December 31, 2024

(In millions)

Fair Value

Valuation Technique

Significant
Unobservable Input(s)

Range

Weighted Average

Liabilities:

Contingent consideration obligations

512.8

Discounted cash flow

Discount rate

6.2% - 6.3%

6.2

Expected timing of achievement of development milestones

2025 - 2030

—

The weighted average discount rates were calculated based on the relative fair values of each distinct contingent consideration obligation related to our acquisition of HI-Bio in July 2024. In addition, we apply various probabilities of technological and regulatory success to the valuation models to estimate the fair values of these contingent consideration obligations, which ranged from approximately 70.0% to near certain probability as of September 30, 2025 and December 31, 2024.

There were no transfers of assets or liabilities into or out of Level 3 as of September 30, 2025 and December 31, 2024.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Quantitative Information about Level 3 Fair Value Measurements

As of June 30, 2025

(In millions)

Fair Value

Valuation Technique

SignificantUnobservable Input(s)

Range

Weighted Average

Liabilities:

Contingent consideration obligations

534.9

Discounted cash flow

Discount rate

5.6% - 5.7%

5.7

Expected timing of achievement of development milestones

2025 - 2030

—

Quantitative Information about Level 3 Fair Value Measurements

As of December 31, 2024

(In millions)

Fair Value

Valuation Technique

SignificantUnobservable Input(s)

Range

Weighted Average

Liabilities:

Contingent consideration obligations

512.8

Discounted cash flow

Discount rate

6.2% - 6.3%

6.2

Expected timing of achievement of development milestones

2025 - 2030

—

There were no transfers of assets or liabilities into or out of Level 3 as of June 30, 2025 and December 31, 2024.

Contingent Consideration Obligations

In connection with our acquisition of HI-Bio in July 2024 we agreed to make additional payments based upon the achievement of certain milestone events. The following table provides a roll forward of the fair value of our contingent consideration obligations, which were classified as Level 3 measurements:

(In millions)	For the Three Months Ended June 30, 2025				For the Six Months Ended June 30, 2025
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
Fair value, beginning of period	$	522.4			$	512.8
(In millions)	2025		2024		2025		2024
Changes in fair value	13.2				22.8
Fair value, beginning of period	$	534.9	$	—	$	512.8	$	—
Payments	(0.7)				(0.7)
Contingent consideration resulting from HI-Bio acquisition	—		485.1		—		485.1
Fair value, end of period	$	534.9			$	534.9
Changes in fair value	5.6		23.8		28.4		23.8
Payments	(149.3)		—		(150.0)		—
Fair value, end of period	$	391.2	$	508.9	$	391.2	$	508.9

Changes in the fair value of our contingent consideration obligations, other than changes due to payments, are ~~recorded~~recognized inas a (gain) loss on fair value remeasurement of contingent consideration in our condensed consolidated statements of income. The fair values of the contingent consideration liabilities were based on a probability-adjusted discounted cash flow calculation using Level 3 fair value measurements and inputs. For additional information on the valuation techniques and inputs utilized in the valuation of our financial assets and liabilities, please read Note 1, Summary of Significant Accounting Policies, to our consolidated financial statements included in our 2024 Form 10-K.

As of ~~June~~September 30, 2025 and December 31, 2024, approximately $~~297~~148.26 million and $291.2 million, respectively, of the fair value of the total contingent consideration obligations were classified as short-term and reflected as a component of accrued expense and other with the remaining $~~237~~242.76 million and $221.6 million, respectively, reflected as a component of other long-term liabilities in our condensed consolidated balance sheets.

For the three and ~~six~~nine months ended ~~June~~September 30, 2025, changes in ~~the~~ fair value of our contingent consideration obligations were primarily due to the passage of time.

During the second quarter of 2025 the first milestone related to the fourth patient dosed in a phase 3 clinical trial of felzartamab for AMR was achieved, resulting in a $150.0 million milestone payment made to the former shareholders of HI-Bio, which was ~~substantially~~ paid during the third quarter of 2025. In October 2025 the second milestone related to the fourth patient dosed in ~~July~~a phase 3 clinical trial of felzartamab for IgAN was achieved, resulting in a $150.0 million milestone payment to be made to the former shareholders of HI-Bio, which we expect will be paid during the fourth quarter of 2025.

29Financial Instruments Not Carried at Fair Value

Other Financial Instruments

Due to the short-term nature of certain financial instruments, the carrying value reflected in our condensed consolidated balance sheets for current accounts receivable, due from anti-CD20 therapeutic programs, other current assets, accounts payable and accrued expense and other, approximates fair value.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Financial Instruments Not Carried at Fair Value

Other Financial Instruments

Debt Instruments

The fair and carrying values of our debt instruments, which are Level 2 liabilities, are summarized as follows:

	As of June 30, 2025				As of December 31, 2024
	As of September 30, 2025				As of December 31, 2024
(In millions)	FairValue		CarryingValue		FairValue		CarryingValue
Current portion:
4.050% Senior Notes due September 15, 2025(1)	$	—	$	—	$	1,741.0	$	1,748.6
Current portion of notes payable	—		—		1,741.0		1,748.6
Non-current portion:
2.250% Senior Notes due May 1, 2030	1,~~351~~367.18		1,495.25		1,295.6		1,494.7
5.050% Senior Notes due January 15, 2031(1)	~~407~~410.18		397.89		—		—
5.750% Senior Notes due May 15, 2035(1)	~~668~~680.72		645.54		—		—
5.200% Senior Notes due September 15, 2045	1,~~007~~026.19		1,101.34		1,008.0		1,101.1
3.150% Senior Notes due May 1, 2050	~~946~~970.02		1,475.35		943.7		1,475.0
3.250% Senior Notes due February 15, 2051	~~450~~458.48		~~478~~479.3		448.9		476.4
6.450% Senior Notes due May 15, 2055(1)	~~721~~748.79		690.31		—		—
Non-current portion of notes payable	5,~~552~~663.16		6,~~283~~285.71		3,696.2		4,547.2
Total notes payable	$	5,~~552~~663.16	$	6,~~283~~285.71	$	5,437.2	$	6,295.8

(1) In May 2025 we issued our 2025 Senior 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 in full our 4.050% Senior Notes due September 15, 2025, prior to maturity. For additional information, please read Note 13, Indebtedness, to these condensed consolidated financial statements.

The fair values of each of our series of Senior Notes were determined through market, observable and corroborated sources. The changes in the fair values of our Senior Notes as of ~~June~~September 30, 2025, compared to December 31, 2024, are primarily related to decreases in U.S. treasury yields, ~~partially~~and ~~offset by increases in~~ credit spreads used to value our Senior Notes since December 31, 2024. For additional information related to our Senior Notes, please read Note 13, Indebtedness, to our consolidated financial statements included in our 2024 Form 10-K.


Note 9:			Financial Instruments

The following table summarizes our financial assets with maturities of less than 90 days from the date of purchase included in cash and cash equivalents in our condensed consolidated balance sheets:

(In millions)	As of ~~June~~September 30, 2025		As of December 31, 2024
Money market funds	$	23,~~234~~116.97	$	1,664.9
Total	$	2,234.9	$	1,664.9
Short-term debt securities	202.9		—
Commercial paper	79.2		—
Total	$	3,398.8	$	1,664.9

The carrying ~~value~~values of our money market funds, ~~approximates~~short-term debt securities and commercial paper, including accrued interest, approximate fair value due to their short-term maturities.

3032

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Our marketable equity securities gains (losses) are recorded in other (income) expense, net in our condensed consolidated statements of income. The following tables summarize our marketable debt and equity securities, classified as available-for-sale:

	As of June 30, 2025
	As of September 30, 2025
(In millions)	AmortizedCost		GrossUnrealizedGains		GrossUnrealizedLosses		FairValue
Marketable debt securities
Corporate debt securities:
Current	$	71.0	$	—	$	—	$	71.0
Government securities:
Current	26.6		—		—		26.6
Total marketable debt securities	$	97.6	$	—	$	—	$	97.6
Marketable equity securities
Marketable equity securities, non-current	$	~~668~~227.78	$	—	$	(~~511~~123.79)	$	~~157~~103.09
Total marketable equity securities	$	~~668~~227.78	$	—	$	(~~511~~123.79)	$	~~157~~103.09


	As of December 31, 2024
(In millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value












Marketable equity securities

Marketable equity securities, non-current	$	668.7	$	—	$	(489.0)	$	179.7
Total marketable equity securities	$	668.7	$	—	$	(489.0)	$	179.7

Summary of Contractual Maturities: Available-for-Sale Debt Securities

The estimated fair value and amortized cost of our marketable debt securities classified as available-for-sale by contractual maturity are summarized as follows:


	As of September 30, 2025
(In millions)	Estimated Fair Value		Amortized Cost
Due in one year or less	$	97.6	$	97.6


Total marketable debt securities	$	97.6	$	97.6

The average maturity of our marketable debt securities classified as available-for-sale as of September 30, 2025, was approximately 2 months.

Strategic Investments

Our strategic investment portfolio includes investments in equity securities of certain biotechnology companies, which are reflected within our disclosures included in Note 8, Fair Value Measurements, to these condensed consolidated financial statements, as well as venture capital funds where the underlying investments are in equity securities of certain biotechnology companies and non-marketable equity securities.

As of ~~June~~September 30, 2025 and December 31, 2024, our strategic investment portfolio was comprised of investments totaling $~~224~~167.01 million and $226.7 million, respectively, which are included in investments and other assets within our condensed consolidated balance sheets.

The decrease in our strategic investment portfolio as of ~~June~~September 30, 2025, compared to December 31, 2024, was primarily due to the decrease in the fair value of our investment in Denali common stock, ~~partially~~as ~~offset~~well byas ~~an increase in~~ the ~~fair~~sale ~~value~~ of our remaining investment in Sage common stock during the third quarter of 2025.

~~Note 10: Derivative Instruments~~33

Foreign Currency Forward Contracts - Hedging Instruments

Due to the global nature of our operations, portions of our revenue and operating expense are recorded in currencies other than the U.S. dollar. The value of revenue and operating expense measured in U.S. dollars is therefore subject to changes in foreign currency exchange rates. We enter into foreign currency forward contracts and foreign currency options with financial institutions with the primary objective to mitigate the impact of foreign currency exchange rate fluctuations on our international revenue and operating expense.

Foreign currency forward contracts and foreign currency options in effect as of June 30, 2025 and December 31, 2024, had durations of 1 to 24 months and 1 to 12 months, respectively. These contracts have been designated as cash flow hedges and unrealized gains and losses on the portion of these foreign currency forward contracts and foreign currency options that are included in the effectiveness test are reported in AOCI. Realized gains and losses of such contracts and options are recognized in revenue when the sale of product in the currency being hedged is recognized and in operating expense when the expense in the currency being hedged is recorded. We recognize all cash flow hedge reclassifications from AOCI and fair value changes of excluded portions in the same line item in our condensed consolidated statements of income that have been impacted by the hedged item.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)


Note 10:			Derivative Instruments

Foreign Currency Forward Contracts - Hedging Instruments

Foreign currency forward contracts and foreign currency options in effect as of September 30, 2025 and December 31, 2024, had durations of 1 to 24 months and 1 to 12 months, respectively. These contracts have been designated as cash flow hedges and unrealized gains and losses on the portion of these foreign currency forward contracts and foreign currency options that are included in the effectiveness test are reported in AOCI. Realized gains and losses of such contracts and options are recognized in revenue when the sale of product in the currency being hedged is recognized and in operating expense when the expense in the currency being hedged is recorded. We recognize all cash flow hedge reclassifications from AOCI and fair value changes of excluded portions in the same line item in our condensed consolidated statements of income that have been impacted by the hedged item.

The notional amount of foreign currency forward contracts and foreign currency options that were entered into to hedge forecasted revenue and operating expense is summarized as follows:

	Notional Amount
(In millions)	As of ~~June~~September 30, 2025		As of December 31, 2024
Euro	$	21,~~024~~524.68	$	1,062.6
British pound	6835.70		133.8
Swiss franc	~~128~~68.50		—
Canadian dollar	209.49		38.6
Total foreign currency forward contracts and options	$	21,~~242~~637.27	$	1,235.0

The pre-tax portion of the fair value of these foreign currency forward contracts and foreign currency options that were included in AOCI in total equity is summarized as follows:

(In millions)	As of ~~June~~September 30, 2025		As of December 31, 2024
Unrealized gains	$	~~17.~~9.5	$	50.6
Unrealized (losses)	(~~153~~112.19)		(0.3)
Net unrealized gains (losses)	$	(~~135~~103.24)	$	50.3

We expect net unrealized losses of approximately $~~135~~103.24 million to be settled over the next 24 months, of which approximately $~~111~~90.18 million of these net unrealized losses are expected to be settled over the next 12 months, with any amounts in AOCI to be reported as an adjustment to revenue or operating expense. We consider the impact of our and our counterparties’ credit risk on the fair value of the contracts as well as the ability of each party to execute its contractual obligations. As of ~~June~~September 30, 2025 and December 31, 2024, credit risk did not materially change the fair value of our foreign currency forward contracts and forward currency options.

~~The following tables summarize the effect of foreign currency forward contracts and forward currency options designated as hedging instruments in our condensed consolidated statements of income:~~34

For the Three Months Ended June 30,
Net Gains/(Losses)Reclassified from AOCI into Operating Income (in millions)					Net Gains/(Losses) Excluded from Effectiveness Testing andRecognized in Operating Income (in millions)
Location	2025		2024		Location	2025		2024
Revenue	$	(22.9)	$	7.6	Revenue	$	(0.8)	$	0.9
Operating expense	6.6		(4.9)		Operating expense	(0.8)		(0.7)
For the Six Months Ended June 30,
Net Gains/(Losses)Reclassified from AOCI into Operating Income (in millions)					Net Gains/(Losses) Excluded from Effectiveness Testing andRecognized in Operating Income (in millions)
Location	2025		2024		Location	2025		2024
Revenue	$	(12.0)	$	10.5	Revenue	$	(0.4)	$	1.1
Operating expense	7.3		(7.0)		Operating expense	(1.8)		(1.9)

Foreign Currency Forward Contracts - Other Derivative Instruments

We also enter into other foreign currency forward contracts, usually with durations of one month or less, to mitigate the foreign currency risk related to certain balance sheet positions. We have not elected hedge accounting for these transactions.

The aggregate notional amount of these outstanding foreign currency forward contracts was $1,045.2 million and $738.7 million as of June 30, 2025 and December 31, 2024, respectively. Net gains of $27.7 million and $35.4 million related to these contracts were recorded as a component of other (income) expense, net for the three and six months ended June 30, 2025, respectively, compared to net losses of $5.7 million and $30.0 million, respectively, in the prior year comparative periods.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

The following tables summarize the effect of foreign currency forward contracts and forward currency options designated as hedging instruments in our condensed consolidated statements of income:


For the Three Months Ended September 30,
Net Gains/(Losses) Reclassified from AOCI into Operating Income (in millions)					Net Gains/(Losses) Excluded from Effectiveness Testing and Recognized in Operating Income (in millions)
Location	2025		2024		Location	2025		2024
Revenue	$	(29.1)	$	(7.6)	Revenue	$	8.0	$	2.9
Operating expense	6.7		(1.5)		Operating expense	—		0.3

For the Nine Months Ended September 30,
Net Gains/(Losses) Reclassified from AOCI into Operating Income (in millions)					Net Gains/(Losses) Excluded from Effectiveness Testing and Recognized in Operating Income (in millions)
Location	2025		2024		Location	2025		2024
Revenue	$	(41.1)	$	2.9	Revenue	$	7.6	$	4.0
Operating expense	14.0		(8.5)		Operating expense	(1.8)		(1.6)

Foreign Currency Forward Contracts - Other Derivative Instruments

The aggregate notional amount of these outstanding foreign currency forward contracts was $1,066.6 million and $738.7 million as of September 30, 2025 and December 31, 2024, respectively. Net losses of $0.5 million and net gains of $34.9 million related to these contracts were recorded as a component of other (income) expense, net for the three and nine months ended September 30, 2025, respectively, compared to net gains of $23.4 million and net losses of $6.6 million, respectively, in the prior year comparative periods.

Summary of Derivative Instruments

While certain of our derivative instruments are subject to netting arrangements with our counterparties, we do not offset derivative assets and liabilities in our condensed consolidated balance sheets. The amounts in the table below would not be substantially different if the derivative assets and liabilities were offset.

The following table summarizes the fair value and presentation in our condensed consolidated balance sheets of our outstanding derivative instruments, including those designated as hedging instruments:

(In millions)	Balance Sheet Location	As of ~~June~~September 30, 2025		As of December 31, 2024
Cash Flow Hedging Instruments:
Asset derivative instruments	Other current assets	$	167.18	$	58.4
Liability derivative instruments	Accrued expense and other	~~118~~87.93		0.3
	Other long-term liabilities	2610.82		—
Other Derivative Instruments:
Asset derivative instruments	Other current assets	151.68		4.1
Liability derivative instruments	Accrued expense and other	41.8		11.4


Note 11:			Property, Plant and Equipment

Property, plant and equipment are recorded at historical cost, net of accumulated depreciation. Accumulated depreciation on property, plant and equipment was $2,~~808~~868.74 million and $2,670.8 million as of ~~June~~September 30, 2025 and December 31, 2024, respectively. For the three and ~~six~~nine months ended ~~June~~September 30, 2025, depreciation expense totaled approximately $66.95 million and $~~138~~204.38 million, respectively, compared to $7172.97 million and $~~141~~213.29 million, respectively, in the prior year comparative periods.

~~Note 12: Leases~~35

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% in 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. The estimated minimum lease payments as a result of the new lease total approximately $1.5 billion over the initial lease term. We have an option to extend the lease for three extension periods of five years each and one six month short-term extension, at then market-based rates. We will account for this lease as a right-of-use asset and lease liability upon the lease commencement date.

For additional information on our accounting policies relating to leases, please read Note 1, Summary of Significant Accounting Policies - Leases, to our consolidated financial statements included in our 2024 Form 10-K.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)


Note 12:			Leases

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. The estimated minimum lease payments as a result of the new lease total approximately $1.5 billion over the initial lease term. We have an option to extend the lease for three extension periods of five years each and one six month short-term extension, at then market-based rates. We will account for this lease as a right-of-use asset and lease liability upon the lease commencement date.


Note 13:			Indebtedness

2025 Senior Notes

On May 12, 2025, we issued senior unsecured notes for an aggregate principal amount of $1.75 billion, consisting of the following:

•$400.0 million of 5.050% Senior Notes due January 15, 2031, valued at 99.981% of par;

•$650.0 million of 5.750% Senior Notes due May 15, 2035, valued at 99.924% of par; and

•$700.0 million of 6.450% Senior Notes due May 15, 2055, valued at 99.657% of par.

Our 2025 Senior Notes are senior unsecured obligations and may be redeemed at our option at any time at 100% of the principal amount plus accrued interest and, until a specified period before maturity, a specified make-whole amount. Our 2025 Senior Notes contain a change-of-control provision that, under certain circumstances, may require us to purchase our 2025 Senior Notes at a price equal to 101% of the principal amount plus accrued and unpaid interest to the date of repurchase.

We incurred approximately $13.9 million of costs associated with this offering which have been recorded as a reduction to the carrying amount of the debt on our condensed consolidated balance ~~sheet~~sheets. These costs will be amortized as additional interest expense using the effective interest rate method over the period from issuance through maturity. The discounts will be amortized as additional interest expense over the period from issuance through maturity using the effective interest rate method.

Interest on our 2031 Senior Notes is payable January 15 and July 15 of each year, commencing January 15, 2026. Interest on our 2035 Senior Notes and 2055 Senior Notes is payable May 15 and November 15 of each year, commencing on November 15, 2025.

4.050% Senior Notes due September 15, 2025

On September 15, 2015, we issued $1.75 billion aggregate principal amount of 4.050% Senior Notes due September 15, 2025, at 99.764% of par. 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 their maturity. No gain or loss was recognized upon redemption.

2023 Term Loan Credit Agreement

In connection with our acquisition of Reata in September 2023 we entered into a $1.5 billion term loan credit agreement. On the closing date of the Reata acquisition we drew $1.0 billion from the 2023 Term Loan, comprised of a $500.0 million floating rate 364-day tranche and a $500.0 million floating rate three-year tranche. The remaining unused commitment of $500.0 million was terminated. As of December 31, 2023, we repaid ~~$350.0 million of the 364--day tranche. The remaining $150.0 million portion of the 364-day tranche was repaid during the first quarter of 2024.~~

Additionally, during the first quarter of 2024 we repaid $250.0 million of the three-year tranche, with the remaining $250.0 million portion being subsequently repaid in full during the second quarter of 2024. For additional information on our acquisition of Reata, please read Note 2, Acquisitions, to our consolidated financial statements included in our 2024 Form 10-K.36

Note 14: Equity

Share Repurchases

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 share repurchases of our common stock during the three and six months ended June 30, 2025 and 2024. Approximately $2.1 billion remained available under our 2020 Share Repurchase Program as of June 30, 2025.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

$350.0 million of the 364--day tranche. The remaining $150.0 million portion of the 364-day tranche was repaid during the first quarter of 2024.


Note 14:			Equity

Share Repurchases

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 share repurchases of our common stock during the three and nine months ended September 30, 2025 and 2024. Approximately $2.1 billion remained available under our 2020 Share Repurchase Program as of September 30, 2025.

Accumulated Other Comprehensive Income (Loss)

The following tables summarize the changes in AOCI, net of tax by component:

	For the Three Months Ended June 30, 2025
	For the Three Months Ended September 30, 2025
(In millions)	Unrealized Gains (Losses) on Cash Flow Hedges,Net of Tax		Unrealized Gains (Losses) on Pension Benefit Obligation, Net of Tax		CurrencyTranslation Adjustments,Net of Tax		Total
Balance, March 31, 2025	$	(6.2)	$	(16.2)	$	(152.1)	$	(174.5)
Other comprehensive income (loss) before reclassifications	(120.4)		0.6		41.6		(78.2)
Amounts reclassified from AOCI	14.6		—		—		14.6
Net current period other comprehensive income (loss)	(105.8)		0.6		41.6		(63.6)
Balance, June 30, 2025	$	(112.0)	$	(15.6)	$	(110.5)	$	(238.1)
	For the Six Months Ended June 30, 2025
Other comprehensive income (loss) before reclassifications	6.3		—		(3.2)		3.1
Amounts reclassified from AOCI	20.2		—		—		20.2
Net current period other comprehensive income (loss)	26.5		—		(3.2)		23.3
Balance, September 30, 2025	$	(85.5)	$	(15.6)	$	(113.7)	$	(214.8)
	For the Nine Months Ended September 30, 2025
(In millions)	Unrealized Gains (Losses) on Cash Flow Hedges, Net of Tax		Unrealized Gains (Losses) on Pension Benefit Obligation, Net of Tax		CurrencyTranslation Adjustments		Total
Balance, December 31, 2024	$	51.6	$	(16.6)	$	(171.2)	$	(136.2)
Other comprehensive income (loss) before reclassifications	(~~167~~161.96)		1.0		6057.75		(~~106~~103.21)
Amounts reclassified from AOCI	424.35		—		—		424.35
Net current period other comprehensive income (loss)	(~~163~~137.61)		1.0		6057.75		(~~101~~78.96)
Balance, June 30, 2025	$	(112.0)	$	(15.6)	$	(110.5)	$	(238.1)
Balance, September 30, 2025	$	(85.5)	$	(15.6)	$	(113.7)	$	(214.8)

	For the Three Months Ended June 30, 2024
(In millions)	Unrealized Gains (Losses) on Cash Flow Hedges,Net of Tax		Unrealized Gains (Losses) on Pension Benefit Obligation,Net of Tax		CurrencyTranslation Adjustments,Net of Tax		Total
Balance, March 31, 2024	$	(10.3)	$	(2.7)	$	(147.5)	$	(160.5)
Other comprehensive income (loss) before reclassifications	22.3		—		(5.6)		16.7
Amounts reclassified from AOCI	(2.2)		—		—		(2.2)
Net current period other comprehensive income (loss)	20.1		—		(5.6)		14.5
Balance, June 30, 2024	$	9.8	$	(2.7)	$	(153.1)	$	(146.0)
	For the Six Months Ended June 30, 2024
(In millions)	Unrealized Gains (Losses) on Cash Flow Hedges, Net of Tax		Unrealized Gains (Losses) on Pension Benefit Obligation, Net of Tax		Currency Translation Adjustments		Total
Balance, December 31, 2023	$	(25.0)	$	(2.6)	$	(126.1)	$	(153.7)
Other comprehensive income (loss) before reclassifications	37.7		(0.1)		(27.0)		10.6
Amounts reclassified from AOCI	(2.9)		—		—		(2.9)
Net current period other comprehensive income (loss)	34.8		(0.1)		(27.0)		7.7
Balance, June 30, 2024	$	9.8	$	(2.7)	$	(153.1)	$	(146.0)

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)


	For the Three Months Ended September 30, 2024
(In millions)	Unrealized Gains (Losses) on Cash Flow Hedges, Net of Tax		Unrealized Gains (Losses) on Pension Benefit Obligation, Net of Tax		Currency Translation Adjustments, Net of Tax		Total
Balance, June 30, 2024	$	9.8	$	(2.7)	$	(153.1)	$	(146.0)
Other comprehensive income (loss) before reclassifications	(49.1)		0.3		41.0		(7.8)
Amounts reclassified from AOCI	8.1		—		—		8.1
Net current period other comprehensive income (loss)	(41.0)		0.3		41.0		0.3
Balance, September 30, 2024	$	(31.2)	$	(2.4)	$	(112.1)	$	(145.7)

	For the Nine Months Ended September 30, 2024
(In millions)	Unrealized Gains (Losses) on Cash Flow Hedges, Net of Tax		Unrealized Gains (Losses) on Pension Benefit Obligation, Net of Tax		Currency Translation Adjustments		Total
Balance, December 31, 2023	$	(25.0)	$	(2.6)	$	(126.1)	$	(153.7)
Other comprehensive income (loss) before reclassifications	(11.4)		0.2		14.0		2.8
Amounts reclassified from AOCI	5.2		—		—		5.2
Net current period other comprehensive income (loss)	(6.2)		0.2		14.0		8.0
Balance, September 30, 2024	$	(31.2)	$	(2.4)	$	(112.1)	$	(145.7)

The following table summarizes the amounts reclassified from AOCI:

(In millions)	Amounts Reclassified from AOCI								Income Statement Location
	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2025		2024		2025		2024
Gains (losses) on cash flow hedges	$	(2229.91)	$	(7.6)	$	(1241.01)	$	102.59	Revenue
	6.6		(4.9)		7.3		(7.0)		Operating expense
	6.7		(1.5)		14.0		(8.5)		Operating expense
	(0.1)		(0.21)		(0.23)		(0.12)		Other (income) expense, net
	1.8		(0.3)		0.6		(0.5)		Income tax (benefit) expense
	2.3		1.1		2.9		0.6		Income tax (benefit) expense
Total reclassifications, net of tax	$	(1420.62)	$	2(8.21)	$	(424.35)	$	2(5.92)

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)


Note 15:			Earnings per Share

Basic and diluted shares outstanding used in our earnings per share calculation are calculated as follows:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Numerator:
Net income attributable to Biogen Inc.	$	~~634~~466.85	$	~~583~~388.65	$	~~875~~1,341.38	$	~~977~~1,365.05
Denominator:
Weighted average number of common shares outstanding	146.56		145.67		146.34		145.45
Effect of dilutive securities:
Time-vested restricted stock units	0.25		0.23		0.34		0.4
Performance stock units settled in stock	—		0.1		~~0.1~~—		0.1
Dilutive potential common shares	0.25		0.34		0.4		0.5
Shares used in calculating diluted earnings per share	~~146~~147.71		~~145~~146.91		146.78		~~145~~146.90

Amounts excluded from the calculation of net income per diluted share because their effects were anti-dilutive were insignificant.


Note 16:			Share-Based Payments

Share-based Compensation Expense

The following table summarizes share-based compensation expense included in our condensed consolidated statements of income:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Research and development	$	3028.18	$	2769.38	$	6291.20	$	54124.75
Selling, general and administrative	4849.06		4561.63		~~100~~149.06		89150.69
Subtotal	78.14		72131.91		~~162~~240.26		~~144~~275.34
Capitalized share-based compensation costs	(3.21)		(2.34)		(69.34)		(58.60)
Share-based compensation expense included in total cost and expense	7475.93		70128.67		~~155~~231.92		~~138~~267.74
Income tax effect	(14.94)		(1324.42)		(3045.93)		(2650.35)
Share-based compensation expense included in net income attributable to Biogen Inc.	$	60.09	$	57104.25	$	~~125~~185.09	$	~~112~~216.49

36In connection with our acquisition of HI-Bio in July 2024 we recognized HI-Bio equity-based compensation expense, inclusive of employer taxes, of approximately $56.4 million attributable to the post-acquisition service period, of which $42.5 million was recognized as a charge to research and development expense with the remaining $13.9 million as a charge to selling, general and administrative expense within our condensed consolidated statements of income for the three and nine months ended September 30, 2024. These amounts were associated with the accelerated vesting of stock options and RSUs previously granted to HI-Bio employees and required no future services to vest. For additional information on our acquisition of HI-Bio, please read Note 2, Acquisitions, to these condensed consolidated financial statements.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

The following table summarizes share-based compensation expense associated with each of our share-based compensation programs:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Time-vested restricted stock units	$	60.61	$	5859.31	$	~~126~~186.78	$	~~115~~174.67
Performance stock units settled in stock	15.05		1113.70		2844.61		2235.2
Employee stock purchase plan	1.68		1.89		56.19		68.32
Performance stock units settled in cash	—		(0.15)		—		(2.05)
Stock options	01.90		01.90		12.8		12.8
Market stock units	—		0.12		—		0.46
Subtotal	78.1		72.9		162.2		144.3
HI-Bio equity awards(1)	—		56.4		—		56.4
Capitalized share-based compensation costs	(3.2)		(2.3)		(6.3)		(5.6)
Subtotal	78.4		131.1		240.6		275.4
Share-based compensation expense included in total cost and expense	$	74.9	$	70.6	$	155.9	$	138.7
Capitalized share-based compensation costs	(3.1)		(2.4)		(9.4)		(8.0)
Share-based compensation expense included in total cost and expense	$	75.3	$	128.7	$	231.2	$	267.4

(1) Relates to the HI-Bio equity-based compensation expense attributable to the post-acquisition service period, associated with the accelerated vesting of stock options and RSUs previously granted to HI-Bio employees and required no future services to vest. For additional information on our acquisition of HI-Bio, please read Note 2, Acquisitions, to these condensed consolidated financial statements.


Note 17:			Income Taxes

2025 OBBBA Tax Provisions

On July 4, 2025, the U.S. signed into law the H.R.1 legislation formally titled "An Act to Provide for Reconciliation Pursuant to Title II of H. Con. Res. 14", commonly referred to as the OBBBA.

The OBBBA contains tax provisions, such as the permanent extension or revision of certain expiring provisions of the Tax Cuts and Jobs Act enacted in 2017, modifications to the international tax framework and the restoration of favorable tax treatment for certain business provisions. The provisions of the OBBBA have multiple effective dates, with certain provisions effective in 2025 and others implemented through 2027. The OBBBA did not result in any material adjustments to our total income tax provision for the three and nine months ended September 30, 2025, and we have adjusted our deferred tax balances to reflect the impacts of the OBBBA enactment.

Tax Rate

A reconciliation between the U.S. federal statutory tax rate and our effective tax rate is summarized as follows:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2025		2024		2025		2024
Statutory rate	21.0	%	21.0	%	21.0	%	21.0	%
State taxes	1.57		12.45		1.7		1.47
Taxes on foreign earnings, including valuation allowances	(75.70)		(611.29)		(87.42)		(57.20)
Tax credits	(1.86)		(1.62)		(1.8)		(21.07)
Purchased inventory valuation step-up and intangible assets	2.14		13.63		2.3		12.50
GILTI	(1.92)		(01.91)		(1.0)		(1.64)
Share-based compensation awards	~~0.1~~—		—		1.71		0.32
Other, including permanent items	1.4		1.2		1.5		0.6
OBBBA enactment	(2.1)		—		(0.7)		—
Effective tax rate	14.7	%	16.5	%	17.0	%	16.0	%
Other, including permanent items	1.1		1.3		1.4		0.6
Effective tax rate	16.3	%	13.9	%	16.8	%	15.4	%

~~Changes in Tax Rate~~40

For the three and six months ended June 30, 2025, compared to the same periods in 2024, the changes in our effective tax rates were partially driven by the favorable deferred tax impacts of decreases in foreign withholding taxes and a foreign valuation allowance in 2025, partially offset by changes in the territorial mix of our profitability.

The six months ended June 30, 2025, compared to the same period in 2024, also reflects the impacts of certain share-based compensation awards that vested during the first quarter of 2025 and a decrease in our estimate of Pillar Two minimum tax liabilities.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Changes in Tax Rate

For the three and nine months ended September 30, 2025, compared to the same periods in 2024, the increases in our effective tax rates were partially driven by changes in the territorial mix of our profitability, partially offset by the impact of the OBBBA enactment.

The nine months ended September 30, 2025, compared to the same period in 2024, also reflects the impacts of certain share-based compensation awards that vested during the first quarter of 2025 and a decrease in our estimate of Pillar Two minimum tax liabilities.

For the three and nine months ended September 30, 2024, our effective tax rates benefited from a decrease in our valuation allowance, partially offset by the impact of certain foreign uncertain tax positions.

Accounting for Uncertainty in Income Taxes

We and our subsidiaries are routinely examined by various taxing authorities. We file income tax returns in various U.S. states and in U.S. federal and other foreign jurisdictions. With few exceptions, we are no longer subject to U.S. federal tax examination for years before 2021 or state, local or non-U.S. income tax examinations for years before 2013.

The U.S. Internal Revenue Service and other national tax authorities routinely examine our intercompany transfer pricing with respect to intellectual property related transactions and it is possible that they may disagree with one or more positions we have taken with respect to such valuations.

It is reasonably possible that we will adjust the value of our uncertain tax positions related to certain transfer pricing, collaboration matters, withholding taxes and other issues as we receive additional information from various taxing authorities, including reaching settlements with such authorities.

We estimate that it is reasonably possible that our gross unrecognized tax benefits, exclusive of interest, could

decrease by up to approximately $35.0 million in the next 12 months as a result of various audit closures, settlements and expiration of the statute of limitations.


Note 18:			Other Consolidated Financial Statement Detail

Other (Income) Expense, Net

Components of other (income) expense, net, are summarized as follows:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Interest income	$	(3231.36)	$	(2011.16)	$	(5687.28)	$	(3749.51)
Interest expense	7267.64		6159.38		~~132~~200.60		~~130~~190.53
(Gains) losses on investments, net	~~(5.~~3).8		30(39.71)		3034.31		6122.32
Foreign exchange (gains) losses, net	10.43		114.39		616.69		2025.76
Other, net	3(15.38)		2.0.8		3(12.80)		34.97
Total other (income) expense, net	$	4834.71	$	8514.28	$	~~117~~151.12	$	~~178~~193.97

The (gains) losses on investments, net, as reflected in the table above, relate to equity securities of certain biotechnology companies, venture capital funds where the underlying investments are in equity securities of certain biotechnology companies and non-marketable equity securities.

The following table summarizes our (gains) losses on investments, net that relate to our equity securities held during the following periods:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Net (gains) losses recognized on equity securities	$	~~(5.~~3).8	$	30(39.41)	$	3034.31	$	6121.09
Less: Net (gains) losses realized on equity securities	—7.0		0(10.69)		(51.4)6		(5.54)
Net unrealized (gains) losses recognized on equity securities	$	(5.3.2)	$	29(28.82)	$	3532.75	$	5527.53

The net unrealized gains recognized during the three months ended June 30, 2025, primarily reflect an increase in the aggregate fair value of our investments in Sage and Denali common stock of approximately $10.1 million.41

The net unrealized losses recognized during the three months ended June 30, 2024, primarily reflect a decrease in the aggregate fair value of our investments in Sage and Sangamo common stock of approximately $51.4 million, partially offset by an increase in the fair value of Denali common stock of approximately $27.0 million.

The net unrealized losses recognized during the six months ended June 30, 2025, primarily reflect a decrease in the aggregate fair value of our investments in Denali common stock of approximately $45.7 million, partially offset by an increase in the fair value of Sage common stock of approximately $23.0 million.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

The net unrealized ~~losses~~gains recognized during the ~~six~~three months ended ~~June~~September 30, ~~2024~~2025, primarily reflect aan ~~decrease~~increase in the aggregate fair value of our ~~investments~~investment in ~~Sage and Sangamo common stock of approximately $68.3 million, partially offset by an increase in the fair value of~~ Denali common stock of approximately $173.68 million.

The net unrealized gains recognized during the three months ended September 30, 2024, primarily reflect an increase in the aggregate fair value of our investments in Denali and Sangamo common stock of approximately $53.3 million, partially offset by a decrease in the fair value of Sage common stock of approximately $22.7 million.

The net unrealized losses recognized during the nine months ended September 30, 2025, primarily reflect a decrease in the aggregate fair value of our investment in Denali common stock of approximately $41.9 million, partially offset by an increase in the fair value of Sage common stock of approximately $23.0 million.

The net unrealized losses recognized during the nine months ended September 30, 2024, primarily reflect a decrease in the aggregate fair value of our investments in Sage common stock of approximately $90.2 million, partially offset by an increase in the fair value of Denali and Sangamo common stock of approximately $70.1 million.

Accrued Expense and Other

Accrued expense and other consists of the following:

(In millions)

As of ~~June~~September 30, 2025

As of December 31, 2024

Revenue-related reserves for discounts and allowances

~~997~~1,062.43

937.5

Employee compensation and benefits

~~260~~310.97

375.8

Collaboration expense

~~179~~268.57

309.0

Royalties and licensing fees

~~200~~320.32

190.2

Current portion of contingent consideration obligations

~~297~~148.26

291.2

Derivative liabilities

~~123~~89.71

11.7

Other

~~601~~574.50

692.3

Total accrued expense and other

2,~~660~~773.56

2,807.7

Other Long-term Liabilities

Other long-term liabilities were $~~799~~761.68 million and $732.3 million as of ~~June~~September 30, 2025 and December 31, 2024, respectively, and included accrued income taxes totaling $~~165~~164.17 million and $156.7 million, respectively.


Note 19:			Collaborative and Other Relationships

Genentech, Inc. (Roche Group)

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, ~~and~~ 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. For purposes of this footnote, we refer to RITUXAN and RITUXAN HYCELA collectively as RITUXAN.

RITUXAN

Genentech and its affiliates are responsible for the worldwide manufacture of RITUXAN as well as all development and commercialization activities as follows:

•U.S.: We have co-exclusively licensed our rights to develop, commercialize and market RITUXAN in the U.S.

•Canada: We have co-exclusively licensed our rights to develop, commercialize and market RITUXAN in Canada.

GAZYVA

The Roche Group and its sub-licensees maintain sole responsibility for the development, manufacture and commercialization of GAZYVA in the U.S. The level of gross sales of GAZYVA in the U.S. has impacted our percentage of the co-promotion profits for RITUXAN and LUNSUMIO, as summarized in the table below.

~~OCREVUS~~42

Pursuant to the terms of our collaboration arrangements with Genentech, we receive a tiered royalty on U.S. net sales from 13.5% and increasing up to 24.0% if annual net sales exceed $900.0 million. There will be a 50.0% reduction to these royalties upon the first entry of an FDA approved biosimilar to OCREVUS.

In addition, we receive a gross 3.0% royalty on net sales of OCREVUS outside the U.S., with the royalty period lasting 11 years from the first commercial sale of OCREVUS on a country-by-country basis.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

OCREVUS

The commercialization of OCREVUS does not impact the percentage of the co-promotion profits we receive for RITUXAN, LUNSUMIO or GAZYVA. Genentech is solely responsible for development and commercialization of OCREVUS and funding future costs. Genentech cannot develop OCREVUS in CLL, non-Hodgkin's lymphoma or rheumatoid arthritis.

OCREVUS royalty revenue is based on our estimates from third party and market research data of OCREVUS sales occurring during the corresponding period. Differences between actual and estimated royalty revenue will be adjusted for in the period in which they become known, which is generally expected to be the following quarter.

LUNSUMIO

We are entitled to a tiered share of co-promotion operating profits and losses in the U.S., as summarized in the table below. In addition, we receive low-single digit royalties on sales of LUNSUMIO outside the U.S.

COLUMVI

Genentech has sole decision-making rights on the commercialization of COLUMVI within the U.S. and we receive tiered royalties in the mid-single digit range on net sales of COLUMVI in the U.S. Under the terms of this agreement, we have no payment obligations. The commercialization of COLUMVI does not impact the percentage of the co-promotion profits we receive for RITUXAN, LUNSUMIO or GAZYVA.

Profit-sharing Formulas

RITUXAN and LUNSUMIO Profit Share

Our current pretax co-promotion profit-sharing formula for RITUXAN and LUNSUMIO in the U.S. provides for a 30.0% share on the first $50.0 million of combined co-promotion operating profits earned each calendar year. As a result of the FDA approval of LUNSUMIO our share of the combined annual co-promotion profits for RITUXAN and LUNSUMIO in excess of $50.0 million varies upon the following events, as summarized in the table below:




After LUNSUMIO Approval until the First Threshold Date	37.5	%
After First Threshold Date until the Second Threshold Date	35.0	%
After Second Threshold Date	30.0	%

First Threshold Date means the earlier of (i) the first day of the calendar quarter following the date U.S. gross sales of GAZYVA within any consecutive 12-month period have reached $500.0 million or (ii) the first date in any calendar year in which U.S. gross sales of LUNSUMIO have reached $150.0 million.

Second Threshold Date means the later of (i) the first date in any calendar year in which U.S. gross sales of LUNSUMIO have reached $350.0 million or (ii) January 1 of the calendar year following the calendar year in which the First Threshold Date occurs.

In March 2023 the First Threshold Date was achieved. As a result, beginning in April 2023 the pre-tax profit share for RITUXAN and LUNSUMIO was 35.0%.

GAZYVA Profit Share

Our current pretax profit-sharing formula for GAZYVA provides for a 35.0% share of operating profits earned each calendar year.

For additional information on our collaboration arrangements with Genentech, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in our 2024 Form 10-K.

~~Ionis Pharmaceuticals, Inc.~~43

2017 SMA Collaboration Agreement

In December 2017 we entered into a collaboration agreement with Ionis to identify new ASO drug candidates for the potential treatment of SMA. Under this agreement, we have options to license therapies arising out of this collaboration and will be responsible for the development and commercialization of such therapies.

In December 2021 we exercised our option with Ionis and obtained a worldwide, exclusive, royalty-bearing license to develop and commercialize salanersen (BIIB115), an investigational ASO in development for SMA.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Ionis Pharmaceuticals, Inc.

2017 SMA Collaboration Agreement

We may pay Ionis up to $155.0 million in additional development and regulatory milestone payments related to salanersen, including a $45.0 million milestone payment due upon the initiation of a Phase 3 trial. Upon commercialization, we may also pay Ionis up to $400.0 million in additional performance-based milestone payments and tiered royalties on potential net sales of such therapies ranging from the mid-teens to high-twenties percentages.

For additional information on our collaboration arrangements with Ionis, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in our 2024 Form 10-K.

Eisai Co., Ltd.

LEQEMBI (lecanemab) Collaboration

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. The FDA granted traditional approval of LEQEMBI in July 2023. Prior to receiving traditional approval, LEQEMBI had been granted accelerated approval by the FDA in January 2023, at which time it became commercially available in the U.S. Outside of the U.S., LEQEMBI is now approved in the E.U. (April 2025), Australia (September 2025), China (January 2024), Japan (September 2023) and other international markets. ~~Additionally, in January 2025 the FDA approved~~ LEQEMBI monthly IV maintenance dosing for the treatment of early Alzheimer's disease was approved in the U.S. and China in January 2025 and September 2025, respectively, and LEQEMBI subcutaneous autoinjector (IQLIK) for weekly maintenance dosing was approved in the U.S. in August 2025.

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.

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.

Upon commercialization of LEQEMBI in the U.S., we began recognizing our 50.0% share of LEQEMBI product revenue, net and cost of sales, including royalties, within Alzheimer's collaboration revenue in our condensed consolidated statements of income, as we are not the principal.

Our share of LEQEMBI sales and marketing expense and development expense are recorded within selling, general and administrative expense and research and development expense, respectively, within our condensed consolidated statements of income.

A summary of development and sales and marketing expense related to the LEQEMBI Collaboration is as follows:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Total development expense incurred by the collaboration related to the advancement of LEQEMBI	$	5470.9	$	9077.67	$	~~107~~178.54	$	~~177~~255.96
Biogen's share of the LEQEMBI Collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	2735.54		4538.48		5389.82		89127.08
Total sales and marketing expense incurred by the LEQEMBI Collaboration	~~171~~176.28		~~137~~164.76		~~348~~525.97		~~311~~476.62
Biogen's share of the LEQEMBI Collaboration sales and marketing expense reflected in selling, general and administrative expense in our condensed consolidated statements of income	8588.73		6882.93		~~174~~262.58		~~155~~238.81

Amounts receivable from Eisai related to the agreements discussed above were approximately $143.4 million and $16.7 million as of June 30, 2025 and December 31, 2024, respectively. Amounts payable to Eisai related to the agreements discussed above were approximately $97.5 million and $138.0 million as of June 30, 2025 and December 31, 2024, respectively.44

For additional information on our collaboration arrangements with Eisai, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in our 2024 Form 10-K.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Amounts receivable from Eisai related to the agreements discussed above were approximately $103.8 million and $16.7 million as of September 30, 2025 and December 31, 2024, respectively. Amounts payable to Eisai related to the agreements discussed above were approximately $97.9 million and $138.0 million as of September 30, 2025 and December 31, 2024, respectively.

UCB

We have a collaboration agreement with UCB, effective November 2003, to jointly develop and commercialize dapirolizumab pegol, an anti-CD40L pegylated Fab, for the potential treatment of SLE and other future agreed indications. Either we or UCB may propose development of dapirolizumab pegol in additional indications. If the parties do not agree to add an indication as an agreed indication to the collaboration, we or UCB may, at the sole expense of the applicable party, pursue development in such excluded indication(s), subject to an opt-in right of the non-pursuing party after proof of clinical activity.

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.

A summary of development expense related to the UCB collaboration agreement is as follows:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Total UCB collaboration development expense	$	1723.82	$	1619.52	$	3962.68	$	3352.13
Biogen's share of UCB collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	8.9		8.3		19.8		16.6
Biogen's share of the UCB collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	11.6		9.5		31.4		26.1

Supernus Pharmaceuticals, Inc. (previously Sage Therapeutics, Inc.)

In November 2020 we entered into a global collaboration and license agreement with Sage to jointly develop and commercialize ZURZUVAE (zuranolone) for the treatment of PPD. In July 2025 Sage was acquired by Supernus. ZURZUVAE was approved in the U.S. in August 2023 and in the E.U. in September 2025.

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, with respect to zuranolone and may pay ~~Sage~~Supernus potential tiered royalties in the high-teens to low-twenties percentages. During the fourth quarter of 2023 we accrued a milestone payment due to ~~Sage~~Supernus of $75.0 million upon the first commercial sale of ZURZUVAE for PPD in the U.S., which was recorded within intangible assets, net in our condensed consolidated balance sheets, and subsequently paid in January 2024.

We share 50.0% of the net collaboration results in the U.S. with ~~Sage~~Supernus, which are recognized in collaboration profit sharing/(loss reimbursement) in our condensed consolidated statements of income. For the three and ~~six~~nine months ended ~~June~~September 30, 2025, we recognized net profit-sharing expense of approximately $1720.87 million and $2748.96 million, respectively, to reflect ~~Sage~~Supernus's 50.0% share of the net collaboration results in the U.S., compared to net profit-sharing expense of approximately $69.50 million and $1120.5 million, respectively, in the prior year comparative periods.

~~A summary of development and sales and marketing expense related to the Sage collaboration is as follows:~~45

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
(In millions)	2025		2024		2025		2024
Total Sage collaboration development expense	$	1.5	$	9.6	$	3.9	$	21.2
Biogen's share of Sage collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	0.8		4.8		2.0		10.6
Total sales and marketing expense incurred by the Sage collaboration	45.7		26.9		89.2		54.5
Biogen's share of Sage collaboration sales and marketing expense reflected in selling, general and administrative expense and collaboration profit sharing/(loss reimbursement) in our condensed consolidated statements of income	22.9		13.5		44.6		27.3

In June 2025 Sage announced it entered into a definitive agreement for Supernus Pharmaceuticals, Inc. to acquire Sage, with the transaction expected to close in the third quarter of 2025.

As set forth in the amended Schedule 13D we filed with the SEC on July 30, 2025, we have disposed of all of our shares of Sage common stock in a block trade.

Denali Therapeutics Inc.

In August 2020 we entered into 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).

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

A summary of development and sales and marketing expense related to the Supernus collaboration is as follows:


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Total Supernus collaboration development expense	$	(1.7)	$	8.4	$	2.2	$	29.6
Biogen's share of the Supernus collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	(0.9)		4.2		1.1		14.8
Total sales and marketing expense incurred by the Supernus collaboration	41.8		28.4		131.0		82.9
Biogen's share of the Supernus collaboration sales and marketing expense reflected in selling, general and administrative expense and collaboration profit sharing/(loss reimbursement) in our condensed consolidated statements of income	20.9		14.2		65.5		41.5

Denali Therapeutics Inc.

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.

A summary of development expense related to the Denali collaboration is as follows:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Total Denali collaboration development expense	$	1211.14	$	1514.49	$	2436.93	$	2944.65
Biogen's share of Denali collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	7.2		9.3		14.9		17.8
Biogen's share of the Denali collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	6.9		8.9		21.8		26.7

Stoke Therapeutics, Inc.

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. Both companies will share responsibility for external clinical development costs, where Stoke is responsible for 70.0% of these development costs and we are responsible for the remaining 30.0% of these development costs.

In connection with the closing of this transaction we made an upfront payment of $165.0 million to Stoke, which was recognized as acquired in-process research and development, upfront and milestone expense within our condensed consolidated statements of income for the ~~six~~nine months ended ~~June~~September 30, 2025. We may also pay Stoke potential development and commercial milestone payments of up to $50.0 million and $335.0 million, respectively, if all the specified milestones set forth in this collaboration are achieved. In addition, we may pay Stoke tiered royalties on potential net sales of any products developed under this collaboration in the low-double digit to high-teen percentages.

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.

A summary of development expense related to the Stoke collaboration agreement is as follows:

(In millions)	For the Three Months Ended ~~June~~September 30, 2025		For the ~~Six~~Nine Months Ended ~~June~~September 30, 2025
Total Stoke collaboration development expense	$	8.9.1	$	1221.89
Biogen's share of Stoke collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	2.6		3.8
Biogen's share of the Stoke collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	2.8		6.6

~~Samsung Bioepis Co., Ltd.~~46

2019 Development and Commercialization Agreement

In December 2019 we completed a transaction with Samsung Bioepis and secured the exclusive rights to commercialize two potential ophthalmology biosimilar products, BYOOVIZ, a ranibizumab biosimilar referencing LUCENTIS, and OPUVIZ, an aflibercept biosimilar referencing EYLEA, in major markets worldwide, including the U.S., Canada, Europe, Japan and Australia. The agreement established that Samsung Bioepis will be responsible for development and will supply both products to us at a pre-specified gross margin of approximately 45.0%.

In October 2024 we notified Samsung Bioepis of our decision to terminate our 2019 Development and Commercialization Agreement (the DCA Agreement) solely within the U.S. and Canada. As a result of this termination we recognized impairment charges of approximately $20.2 million, which were recorded within amortization and impairment of acquired intangible assets within our consolidated statements of income for the year ended December 31, 2024, included in our 2024 Form 10-K. Biogen will transfer commercialization rights for BYOOVIZ and OPUVIZ in the U.S. and Canada back to Samsung Bioepis over a period of up to 18 months. During this transition period, we will continue to commercialize BYOOVIZ. The termination does not impact the other markets in the DCA Agreement.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Samsung Bioepis Co., Ltd.

2019 Development and Commercialization Agreement

In October 2024 we notified Samsung Bioepis of our decision to terminate our 2019 Development and Commercialization Agreement (the DCA Agreement) solely within the U.S. and Canada. As a result of this termination we recognized impairment charges of approximately $20.2 million, which were recorded within amortization and impairment of acquired intangible assets within our condensed consolidated statements of income for the three and nine months ended September 30, 2024. Biogen will transfer commercialization rights for BYOOVIZ and OPUVIZ in the U.S. and Canada back to Samsung Bioepis over a period of up to 18 months. During this transition period, we will continue to commercialize BYOOVIZ. The termination does not impact the other markets in the DCA Agreement.

We may pay Samsung Bioepis up to approximately $150.0 million for achieving additional sales-based milestones associated with the remaining major markets covered by the agreement.

2013 Commercial Agreement

In December 2013 we entered into an agreement with Samsung Bioepis to commercialize, over a 10-year term, three anti-TNF biosimilar product candidates which include IMRALDI, an adalimumab biosimilar referencing HUMIRA, FLIXABI, an infliximab biosimilar referencing REMICADE, and BENEPALI, an etanercept biosimilar referencing ENBREL, in Europe.

In July 2024 we exercised an option to extend this agreement by an additional five years and paid Samsung Bioepis an option exercise fee of $60.0 million, which was recognized in intangible assets, net within our condensed consolidated balance sheets as of December 31, 2024.

We reflect revenue on sales of BENEPALI, IMRALDI and FLIXABI to third parties in product revenue, net in our condensed consolidated statements of income and record the related cost of revenue and sales and marketing expense in our condensed consolidated statements of income to their respective line items when these costs are incurred. Royalty payments to AbbVie on sales of IMRALDI are recognized in cost of sales within our condensed consolidated statements of income.

We share 50.0% of the profit or loss related to our 2013 commercial agreement with Samsung Bioepis, which is recognized in collaboration profit sharing/(loss reimbursement) in our condensed consolidated statements of income. For the three and ~~six~~nine months ended ~~June~~September 30, 2025, we recognized net profit-sharing expense of approximately $5766.25 million and $~~105~~171.27 million, respectively, to reflect Samsung Bioepis' 50.0% sharing of the net collaboration profits, compared to net profit-sharing expense of approximately $5560.93 million and $~~116~~176.58 million, respectively, in the prior year comparative periods.

Other Services

Simultaneous with the formation of Samsung Bioepis, we also entered into a license agreement with Samsung Bioepis. Under this license agreement, we granted Samsung Bioepis an exclusive license to use, develop, manufacture and commercialize biosimilar products created by Samsung Bioepis using Biogen product-specific technology. In exchange, we receive single-digit royalties on biosimilar products developed and commercialized by Samsung Bioepis. Royalty revenue under the license agreement is recognized as a component of contract manufacturing, royalty and other revenue in our condensed consolidated statements of income.

Amounts receivable from Samsung Bioepis related to the agreements discussed above were approximately $54.08 million and $7.6 million as of ~~June~~September 30, 2025 and December 31, 2024, respectively. Amounts payable to Samsung Bioepis related to the agreements discussed above were ~~zero~~$45.3 million and $60.8 million as of ~~June~~September 30, 2025 and December 31, 2024, respectively.

For additional information on our collaboration arrangements with Samsung Bioepis and our other significant collaboration arrangements, please read Note 19, Collaborative and Other Relationships, to our consolidated financial statements included in our 2024 Form 10-K.

~~Other Research and Discovery Arrangements and Funding Arrangements~~47

These arrangements may include the potential for future milestone payments based on the achievement of certain clinical and commercial development payable over a period of several years.

Royalty Pharma Funding Arrangement

In February 2025 we entered into a funding agreement with Royalty Pharma under which we will receive up to $200.0 million in 2025 and 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. We plan to recognize this funding as a reduction to research and development expense within our condensed consolidated statements of income, proportionate to the related expense. For the three and six months ended June 30, 2025, we recorded reductions to research and development expense of $50.0 million and $100.0 million, respectively, within our condensed consolidated statements of income.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Other Research and Discovery Arrangements and Funding Arrangements

These arrangements may include the potential for future milestone payments based on the achievement of certain clinical and commercial development payable over a period of several years.

Royalty Pharma Funding Arrangement

In February 2025 we entered into a funding agreement with Royalty Pharma under which we will receive up to $200.0 million in 2025 and 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. We plan to recognize this funding as a reduction to research and development expense within our condensed consolidated statements of income, proportionate to the related expense. For the three and nine months ended September 30, 2025, we recorded reductions to research and development expense of $50.0 million and $150.0 million, respectively, within our condensed 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 a total of $250.0 million. The milestone payments due upon approval will be recorded as a component of other (income) expense, net within our condensed 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 condensed consolidated statements of income.

MorphoSys AG

As part of our acquisition of HI-Bio in July 2024, we acquired HI-Bio's pre-existing in-license commitments under third-party agreements with MorphoSys, which included tiered royalties on potential future sales ranging from high-single digit to mid-teen percentages, as well as potential development, regulatory and commercial milestone payments of up to $130.0 million, $230.0 million and $640.0 million, respectively. These amounts included milestone payments due upon the first patient dosed in a Phase 3 clinical trial of felzartamab in a first and second indication of $35.0 million and $30.0 million, respectively.

During the first quarter of 2025 we accrued a milestone payment due to MorphoSys of $35.0 million upon the first patient dosed in a Phase 3 clinical trial of felzartamab for the treatment of AMR, which was recorded within acquired in-process research and development, upfront and milestone expense in our condensed consolidated statements of income for the ~~six~~nine months ended ~~June~~September 30, 2025, and ~~subsequently~~ paid in April 2025.

During the second quarter of 2025 we accrued a milestone payment due to MorphoSys of $30.0 million upon the first patient dosed in a Phase 3 clinical trial of felzartamab for the treatment of IgAN, which was recorded within acquired in-process research and development, upfront and milestone expense in our condensed consolidated statements of income for the ~~three~~nine ~~and six~~ months ended ~~June~~September 30, 2025, and ~~subsequently~~ paid in July 2025.

City Therapeutics, Inc.

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 combined with our proprietary drug delivery technology. The collaboration will initially focus on a single target that mediates key ~~central~~CNS ~~nervous system~~ 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.

In connection with the closing of this transaction we made an upfront payment of $16.0 million to City Therapeutics, which was recognized as acquired in-process research and development, upfront and milestone expense within our condensed consolidated statements of income for the ~~three~~nine ~~and six~~ months ended ~~June~~September 30, 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 condensed consolidated balance sheets as of ~~June~~September 30, 2025.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

We may also pay City Therapeutics potential research, development and sales-based milestone payments of up to $21.5 million, $360.0 million and $625.0 million, respectively, plus tiered royalties on potential future net sales, ranging from high-single digit to low-double digit percentages.

We also have the option to select one additional target in the collaboration, subject to an additional payment and availability of the target.


Note 20:			Investments in Variable Interest Entities

Unconsolidated Variable Interest Entities

We have relationships with various variable interest entities that we do not consolidate as we lack the power to direct the activities that significantly impact the economic success of these entities. These relationships include investments in certain biotechnology companies and research collaboration agreements.

45As of September 30, 2025 and December 31, 2024, the carrying value of our investments in certain biotechnology companies representing potential unconsolidated variable interest entities totaled $44.8 million and $23.6 million, respectively. Our maximum exposure to loss related to these variable interest entities is limited to the carrying value of our investments.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

As of June 30, 2025 and December 31, 2024, the carrying value of our investments in certain biotechnology companies representing potential unconsolidated variable interest entities totaled $49.3 million and $23.6 million, respectively. Our maximum exposure to loss related to these variable interest entities is limited to the carrying value of our investments.

We have also entered into research collaboration agreements with certain variable interest entities where we are required to fund certain development activities. These development activities are included in research and development expense in our condensed consolidated statements of income as they are incurred. We have provided no financing to these variable interest entities other than previous contractually required amounts.

For additional information on our investments in variable interest entities, please read Note 20, Investments in Variable Interest Entities, to our consolidated financial statements included in our 2024 Form 10-K.


Note 21:			Litigation

We are currently involved in various claims, investigations and legal proceedings, including the matters described below. For information as to our accounting policies relating to claims and legal proceedings, including use of estimates and contingencies, please read Note 1, Summary of Significant Accounting Policies, to our consolidated financial statements included in our 2024 Form 10-K.

With respect to some loss contingencies, an estimate of the possible loss or range of loss cannot be made until management has further information, including, for example, (i) which claims, if any, will survive dispositive motion practice; (ii) information to be obtained through discovery; (iii) information as to the parties' damages claims and supporting evidence; (iv) the parties’ legal theories; and (v) the parties' settlement positions. If an estimate of the possible loss or range of loss can be made at this time, it is included in the potential loss contingency description below.

The claims and legal proceedings in which we are involved also include challenges to the scope, validity or enforceability of the patents relating to our products, pipeline or processes and challenges to the scope, validity or enforceability of the patents held by others. These include claims by third parties that we infringe their patents. An adverse outcome in any of these proceedings could result in one or more of the following and have a material impact on our business or consolidated results of operations and financial position: (i) loss of patent protection; (ii) inability to continue to engage in certain activities; and (iii) payment of significant damages, royalties, penalties and/or license fees to third parties.

Loss Contingencies

Securities Litigation ~~asserted against Biogen~~

We and certain current and former officers are defendants in three securities actions pending in the District Court, one filed by Nadia Shash and Amjad Khan in November 2020, which relates to statements about ADUHELM, one filed by the Oklahoma Firefighters Pension and Retirement System in February 2022, which relates to statements about ADUHELM, and one filed by Thomas Allen Gray in June 2024, which relates to statements about LEQEMBI, TECFIDERA and VUMERITY. All allege violations of federal securities laws under 15 U.S.C. §78j(b) and §78t(a) and 17 C.F.R. §240.10b-5 and seek declarations of the actions as class actions and monetary relief.

~~Derivative Actions~~49

We and members of the Board of Directors are named as defendants in five derivative actions pending in the District Court, one filed by The Booth Family Trust in February 2022, one filed by Elaine Wang in July 2022, one filed by Jonathan Blaufarb (Blaufarb I) in July 2024, one filed by Lawrence Hollin in October 2024 and one filed by Jonathan Blaufarb (Blaufarb II) in October 2024. The Booth, Wang and Blaufarb II actions relate to ADUHELM and other matters, and the Blaufarb I and Hollin actions relate to statements about LEQEMBI, our compliance controls, 2023 earnings guidance and other matters. The actions allege breach of fiduciary duty, waste of corporate assets and other common law claims, and violations of the Securities Exchange Act of 1934, 15 U.S.C. §78a et seq. The actions seek declaratory and injunctive relief, monetary relief payable to Biogen, and attorneys’ fees and costs payable to the plaintiffs. All derivative actions are stayed.

IMRALDI Patent Litigation

IMRALDI is an adalimumab biosimilar manufactured by Samsung Bioepis that Biogen commercializes in Europe.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

InDerivative June 2022 Fresenius Kabi filed a claim for damages and injunctive relief against Biogen France SAS in the Tribunal de Grande Instance de Paris alleging infringement of the French counterpart of EP ‘3 145 488 Patent (the EP '488 Patent) by a formulation of IMRALDI no longer commercialized in France. Fresenius Kabi alleges damages of €13,450,000 plus interest and costs. Biogen disputes infringement and the validity of the patent.Actions

InWe ~~May~~and ~~2025~~members of the ~~Higher~~Board ~~Regional~~of Directors are named as defendants in five derivative actions pending in the District Court, ofone ~~Düsseldorf~~filed ~~held~~by ~~that~~The aBooth ~~formulation~~Family ofTrust ~~IMRALDI~~in noFebruary ~~longer~~2022, ~~commercialized~~one filed by Elaine Wang in ~~Germany~~July ~~infringes~~2022, ~~the~~one ~~German~~filed ~~counterpart~~by ofJonathan ~~the~~Blaufarb EP(Blaufarb ~~'488~~I) ~~Patent~~in July 2024, one filed by Lawrence Hollin in October 2024 and ~~ordered~~one anfiled ~~injunction~~by ~~against~~Jonathan ~~infringement~~Blaufarb (Blaufarb II) in October 2024. The Booth, Wang and aBlaufarb ~~declaration~~II ofactions ~~Fresenius~~relate ~~Kabi's~~to ~~right~~ADUHELM and other matters, and the Blaufarb I and Hollin actions relate to ~~seek~~statements ~~damages~~about LEQEMBI, our compliance controls, 2023 earnings guidance and other matters. ~~Biogen~~The ~~has~~actions ~~requested~~allege ~~review~~breach of ~~the~~fiduciary ~~decision~~duty, bywaste ~~Germany's~~of ~~Federal~~corporate ~~Court~~assets ofand ~~Justice~~other common law claims, and ~~has~~violations of the ~~right~~Securities Exchange Act of 1934, 15 U.S.C. §78a et seq. The actions seek declaratory and injunctive relief, monetary relief payable to ~~challenge~~Biogen, ~~the~~and ~~validity~~attorneys’ offees and costs payable to the ~~patent~~plaintiffs. inAll aderivative ~~separate~~actions ~~proceeding~~are stayed.

IMRALDI Patent Litigation

IMRALDI is an adalimumab biosimilar manufactured by Samsung Bioepis that Biogen commercializes in Europe.

In June 2022, Fresenius Kabi filed a claim for damages and injunctive relief against Biogen France SAS in the Tribunal de Grande Instance de Paris alleging infringement of the French counterpart of EP ‘3 145 488 Patent (the EP '488 Patent) by a formulation of IMRALDI no longer commercialized in France. Fresenius Kabi alleges damages of €13,450,000 plus interest and costs. Biogen disputes infringement and the validity of the patent.

In May 2025 the Higher Regional Court of Düsseldorf held that a formulation of IMRALDI we no longer commercialize in Germany infringed the German counterpart of the EP '488 Patent and enjoined infringement and declared Fresenius Kabi's right to seek damages. Biogen has requested review of the decision by Germany's Federal Court of Justice and has challenged the validity of the patent in a separate proceeding.

Litigation with Former Convergence Shareholders

In 2015 Biogen acquired Convergence, a U.K. company. In 2019 Shareholder Representative Services LLC, on behalf of ~~the~~ former shareholders of Convergence, asserted claims of $200.0 million for alleged breaches of the contract pursuant to which we acquired Convergence. Inand in June 2023 ~~Shareholder~~it ~~Representative Services LLC~~ and 24 former Convergence shareholders filed a suit against us in the High Court of Justice of England and Wales asserting one of the 2019 claims and seeking payment of $49.9 million, plus interest and costs. ~~Trial~~A ~~concluded in May 2025 and a~~ final decision is pending.

Humana Patient Assistance Litigation

In February 2025 Humana filed suit against Biogen Inc., Biogen U.S. Corp. and Advanced Care Scripts, Inc. in Jefferson Circuit Court in Kentucky alleging damages related to ~~our~~ providing MS patients with free medications and ~~making~~to charitable contributions to non-profit organizations that ~~assist~~provide financial assistance to MS patients. Humana alleges breach of contract, fraud and other claims under various state laws and seeks damages, attorneys' fees and costs.

Genentech Litigation

In February 2023 Genentech, Inc. filed suit ~~against us~~ in the U.S. District Court for the Northern District of California ~~and~~claiming ~~claims~~ that it iswas owed royalties ~~of approximately $88.3 million~~ on sales of TYSABRI that occurred after the expiration of a patent licensed by Genentech to Biogen,. In September 2025 the Court ordered that Biogen is liable to pay Genentech damages of approximately $88.3 million plus interest ~~and~~(approximately ~~costs~~$35.9 million ~~The~~as ~~parties~~of ~~have~~September ~~agreed~~30, to2025), ~~submit~~which ~~the~~continues ~~case~~ to ~~the~~accrue. ~~court~~Final ~~for~~judgment ~~decision~~has not yet entered.

Lender Litigation

In April 2025, by agreement of the parties, the court discontinued with prejudice the previously disclosed suit filed in 2024 by BioPharma Credit PLC, BPCR Limited Partnership, and BioPharma Credit Investments V (Master) LP against us and Reata Pharmaceuticals, Inc. in the Supreme Court of the State of New York alleging breach of a loan agreement ~~with Reata~~.

Antitrust Litigation

In August 2024 we were sued by Local No. 1 Health Fund and in September 2024 we were sued by the Mayor and City Council of Baltimore, New York State Teamsters Council Health and Hospital Fund, Teamsters Local 237 Welfare Fund and Teamsters Local 237 Retirees' Benefit Fund, in cases filed in the U.S. District Court for the Northern District of Illinois. After the cases were consolidated for pre-trial purposes, these plaintiffs and UFCW Local 1500 Welfare Fund sued us in a consolidated amended complaint filed in November 2024. The plaintiffs allege violations of federal antitrust laws including 15 U.S.C. §§ 1, 2 and 13(c) and of various state laws, based on our contracts with pharmacy benefit managers related to TECFIDERA and VUMERITY. Plaintiffs seek declarations of the actions as class actions, monetary, declaratory and equitable relief, and attorneys' fees and costs. In June 2025 the court dismissed the case without prejudice and granted the plaintiffs leave to amend the complaint.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

pharmacy benefit managers related to TECFIDERA and VUMERITY. Plaintiffs seek declarations of the actions as class actions, monetary, declaratory and equitable relief, and attorneys' fees and costs. In June 2025 the court dismissed the case without prejudice and granted the plaintiffs leave to amend the complaint. In August 2025 plaintiffs filed a second amended complaint adding Jacksonville Police Officers and Fire Fighters Health Insurance Trust as a plaintiff, alleging violation of the same laws as alleged in the dismissed complaint, and adding a claim under the Racketeer Influenced and Corrupt Organizations Act, 18 U.S.C. §1962(c). The plaintiffs filed a third amended complaint in October 2025, removing the New York State Teamsters Council Health and Hospital Fund as a party.

In September 2025 Walgreen Co. and The Kroger Co. filed a complaint alleging violations of 15 U.S.C. §§ 1 and 2 based on our contracts with pharmacy benefit managers related to TECFIDERA and VUMERITY and seeking monetary, declaratory and equitable relief, and attorneys' fees and costs.

Neurimmune Litigation

In May 2025 we filed suit against Neurimmune Holding AG and Neurimmune Subone AG (collectively, "Neurimmune") in the District Court seeking declaratory judgment and permanent injunctive relief regarding our rights under a terminated collaboration agreement related to aducanumab. In September 2025 Neurimmune asserted counterclaims for declaratory judgment, breach of contract and unfair competition under Massachusetts G.L. 93A and seeking monetary, declaratory and equitable relief and attorneys' fees and costs.

TECFIDERA E.U. Litigation

In November 2023 we sued Neuraxpharm Pharmaceuticals S.L. and Neuraxpharm Netherlands B.V. (collectively, Neuraxpharm), Zaklady Farmaceutyzne Polpharma S.A. (Polpharma), Sandoz B.V. (Sandoz), Mylan Ireland Ltd. and Mylan B.V. in the District Court of Amsterdam, Netherlands for damages, alleging violation of our regulatory marketing protection by their sales of generic versions of TECFIDERA. In March 2024 we obtained an injunction against Sandoz enjoining Netherlands sales of its generic version of TECFIDERA. In October 2024 Neuraxpharm, Polpharma and Sandoz counterclaimed for damages based on our actions to enforce TECFIDERA's regulatory marketing protection.

In May 2024 we obtained an injunction in the Danish Maritime and Commercial High Court against Sandoz A/S (reversed on appeal) enjoining Danish sales of its generic version of TECFIDERA and in June 2024 we sued Sandoz A/S for damages, alleging violation of our regulatory marketing protection. In November 2024 Sandoz A/S counterclaimed for damages based on our actions to enforce TECFIDERA's regulatory marketing protection. These cases are stayed.

In September 2025 the European General Court annulled the May 2023 European Commission decision granting TECFIDERA an additional year of regulatory marketing protection extending until February 2025.

Other Matters

Government Investigations

In April 2025 the SEC Division of Enforcement informed us that it has closed the matter in which we had received subpoenas seeking information relating to ADUHELM and its launch and our equity plans, and in April and May 2025 the DOJ and SEC informed us that they closed the matters in which we had received subpoenas seeking information relating to our business operations in several foreign countries.

The Italian Competition Authority is investigating Biogen and other companies in relation to our biosimilar product BYOOVIZ.

47In September 2025 we received a Civil Investigative Demand from the Louisiana Department of Justice for information regarding our policies relating to the purchase of drugs by healthcare organizations that are covered entities under Section 340B of the Public Health Service Act.

TYSABRI Biosimilar Patent Matter

In September 2022 we filed an action in the U.S. District Court for the District of Delaware against Sandoz Inc., other Sandoz entities and Polpharma Biologics S.A. under the Biologics Price Competition and Innovation Act, 42 U.S.C. §262, seeking a declaratory judgment of patent infringement. No trial date is set.

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

TYSABRI Biosimilar Patent Matter

Hatch-Waxman Act Litigation relating to VUMERITY Orange-Book Listed Patents

In July 2023 Biogen and Alkermes Pharma Ireland Limited filed patent infringement proceedings relating to VUMERITY Orange-Book listed patents (U.S. Patent Nos. 8,669,281, 9,090,558 and 10,080,733) pursuant to the Drug Price Competition and Patent Term Restoration Act of 1984 (the Hatch-Waxman Act) in the U.S. District Court for the District of Delaware against Zydus Worldwide DMCC, Zydus Pharmaceuticals (USA) Inc. and Zydus Lifesciences Limited. In July 2025 the parties reached a settlement and the court dismissed the case pursuant to the parties' stipulation of dismissal.

Product Liability and Other Legal Proceedings

We are also involved in product liability claims and other legal proceedings incidental to our normal business activities. While the outcome of any of these proceedings cannot be accurately predicted, we do not believe the ultimate resolution of any of these existing matters would have a material adverse effect on our business or financial condition.

Eisai Matter

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.

Product Liability and Other Legal Proceedings


Note 22:			Segment Information

We operate and are managed as one operating segment, and derive revenue from activities related to the discovery, development and delivery of innovative therapies for people living with serious and complex diseases.

Our research and development organization is responsible for the research and discovery of new product candidates and supports development and registration efforts for potential future products. Our pharmaceutical, operations and technology organization manages the development of the manufacturing processes, clinical trial supply, commercial product supply, distribution, buildings and facilities. Our commercial organization is responsible for U.S. and international development of our commercial products. We are also supported by corporate staff functions.

Our CEO, as the CODM, manages and allocates resources to the operations of our company on a total company basis by assessing the overall level of resources available and deciding how to best deploy these resources across functions, therapeutic areas and research and development projects that are in line with our long-term company-wide strategic goals. In making these decisions, our CEO is provided with and uses consolidated financial information for purposes of evaluating performance, forecasting future period financial results, allocating resources and setting incentive targets. The CODM performs this assessment based on the segment’s net income. Through this analysis, which includes a comparison to budgeted results, the CODM assesses performance and how to allocate resources across the functions discussed above. The measure of segment assets used in determining how to manage and allocate resources is reported within our condensed consolidated balance sheets as total assets.

The table presented below, which was prepared in accordance with the accounting policies discussed in Note 1, Summary of Significant Accounting Policies, to our consolidated financial statements included in our 2024 Form 10-K, contains additional information on enterprise-wide disclosures about product revenue, other revenue and long-lived assets, as well as our segment’s revenue and profits, including significant segment expense and other segment items. Revenue is primarily attributed to individual countries based on location of the customer or licensee.

4852

Table of Contents

BIOGEN INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited, continued)

Additional Segment Information

The following table includes additional information about reported segment revenue, significant segment expense and segment measure of profitability:

For the Three Months Ended June 30,

For the Six Months Ended June 30,

For the Three Months Ended September 30,

For the Nine Months Ended September 30,

(In millions)

2025

2024

2025

2024

Total revenue

2,~~645~~534.57

2,~~464~~465.98

57,~~076~~611.52

47,~~755~~221.42

Less cost and expense:

Cost of sales, excluding amortization and impairment of acquired intangible assets:

Product cost of sales

~~415~~384.0

~~358~~468.42

~~877~~1,261.2

~~736.~~1,204.3

Royalty cost of sales

~~190~~290.04

~~187~~170.65

~~357~~647.15

~~352~~522.16

Research and development:

Research and discovery

4641.60

4548.73

90131.9

93141.36

Early stage programs

5159.9

6664.61

~~124~~184.32

~~150~~214.78

Late stage programs

4460.64

4656.73

94154.04

79135.36

Marketed products

87107.7

~~170~~126.0

~~177~~284.29

~~288~~414.1

Other research and development costs(1)

~~168~~167.21

~~176~~221.45

~~346~~513.78

~~339~~560.49

Acquired in-process research and development, upfront and milestone expense

462.61

826.5

~~247~~249.34

1642.05

Selling, general and administrative

~~583~~594.8

~~553~~588.84

1,~~156~~751.31

1,~~135~~723.37

Other segment expense(2)

~~376~~360.38

~~267~~307.65

~~730~~1,091.20

~~588~~895.16

Net Income attributable to Biogen Inc.

~~634~~466.85

~~583~~388.65

~~875~~1,341.38

~~977~~1,365.05

(1) Other research and development costs primarily consist of indirect costs incurred in support of overall research and development activities and non-specific programs, including activities that benefit multiple programs, such as management costs, as well as depreciation, information technology and facility-based expenses and are not allocated to a specific program or stage.

(2) Other segment expense includes: amortization and impairment of acquired intangible assets; collaboration profit sharing/(loss reimbursement); (gain) loss on fair value remeasurement of contingent consideration; restructuring charges; gain on sale of priority review voucher, net; other (income) expense, net; and income tax (benefit) expense.

49Note 23: Subsequent Events

Vanqua Bio, Inc.

In October 2025 we entered into a license agreement with Vanqua to acquire the worldwide rights to Vanqua's preclinical oral C5aR1 antagonist compound. In connection with the closing of this transaction, we expect to make an upfront payment to Vanqua of $70.0 million during the fourth quarter of 2025, which will be recognized within acquired in-process research and development, upfront and milestone expense in our condensed consolidated statements of income.

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, effective as of January 2026.

We expect to recognize a minimal gain within our condensed consolidated statements of income during the fourth quarter of 2025.

Table of Contents

ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion should be read in conjunction with our unaudited condensed consolidated financial statements (condensed consolidated financial statements) and the accompanying notes beginning on page 8 of this quarterly report on Form 10-Q and our audited consolidated financial statements and the accompanying notes included in our 2024 Form 10-K.

The results of operations of HI-Bio, along with the estimated fair values of the assets acquired and liabilities assumed in the acquisition, have been included in our condensed consolidated financial statements since the closing of the HI-Bio acquisition on July 2, 2024.

EXECUTIVE SUMMARY

INTRODUCTION

For additional information on our collaboration arrangements, please read Note 19, Collaborative and Other Relationships, to our condensed 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. Solothurn is operational and has been approved for the manufacture of LEQEMBI. 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, North Carolina. 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.

5054

Table of Contents

BUSINESS ENVIRONMENT

The biopharmaceutical industry and the markets in which we operate are intensely competitive. Many of our competitors are working to develop or have commercialized products similar to those we market. In addition, the commercialization of certain of our own approved products, products of our collaborators and pipeline product candidates may negatively impact future sales of our existing products.

Our products and revenue streams continue to face increasing competition in many markets from the introduction of new originator therapies, generics, 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 branded products. Accordingly, the introduction of such products as well as other lower-priced competing products has, and in the future, may significantly reduce both the price that we are able to charge for our products and the volume of products we sell, which ~~will~~can negatively impact our revenue. 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.

Sales of our products depend, to a significant extent, on the availability and extent of adequate coverage, pricing and reimbursement from government health administration authorities, private health insurers and other organizations. When a new pharmaceutical product is approved, the availability of government and private reimbursement for that product may be uncertain, as is the pricing and amount for which that product will be reimbursed.

Drug prices are under significant scrutiny in the markets in which our products are prescribed; for example the IRA has certain provisions related to drug pricing, including the ability for the U.S. government to set prices for certain drugs in Medicare. We expect drug pricing and other ~~health~~healthcare ~~care~~ costs will continue to be subject to political and societal pressures on a global basis. ~~Additionally,~~As ~~our ability to set~~ the ~~price~~policy ~~for~~environment ~~our~~remains ~~products~~dynamic, ~~varies~~we ~~significantly~~will ~~from~~continue ~~country~~ to ~~country~~monitor ~~and,~~how asuncertainty awith ~~result,~~respect soto ~~can~~how the ~~price or reimbursement of our products~~U.S. ~~Governments~~and ~~may~~foreign ~~use~~tariffs aand ~~variety of cost-containment measures to control~~ the ~~cost of products, including price cuts, mandatory rebates, value-based pricing and reference pricing (i~~U.eS., ~~referencing prices in other countries~~ and ~~using~~international ~~those~~pricing ~~reference~~may ~~prices~~impact toour ~~set~~business ain ~~price)~~the future.

Additionally, our ability to set the price for our products varies significantly from country to country and, as a result, so can the price or reimbursement of our products. Governments may use a variety of cost-containment measures to control the cost of products, including price cuts, mandatory rebates, value-based pricing and reference pricing (i.e., referencing prices in other countries and using those reference prices to set a price).

Our failure to obtain or maintain adequate coverage, pricing or reimbursement for our products could have an adverse effect on our business, reputation, revenue and results of operations, could curtail or eliminate our ability to adequately fund research and development programs for the discovery and commercialization of new products and/or could cause a decline or volatility in our stock price.

In addition to the impact of competition, pricing actions and other measures being taken worldwide designed to reduce healthcare costs and limit the overall level of government expenditures, our sales and operations could also be affected by other risks of doing business internationally, including the impact of public health epidemics on employees, the global economy and the delivery of healthcare treatments, geopolitical events, tariffs, supply chain disruptions, foreign currency exchange fluctuations, changes in intellectual property legal protections and changes in trade regulations and procedures.

For a detailed discussion on our business environment, please read Item 1. Business, in our 2024 Form 10-K. 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. We are defending the validity of our EP 2 653 873 patent related to TECFIDERA which expires in 2028 in opposition proceedings inbefore the Technical Boards of Appeal of the European Patent Office in November 2025. We are also engaged in litigation in Europe to defend and enforce national counterparts of our EP 2 653 873 patent, with mixed results as we have been unsuccessful in enjoining generic entry in several significant European markets.

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

Table of Contents

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 in certain international markets.

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.

Table of Contents

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 share 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 condensed consolidated financial statements included in this report.

BUSINESS UPDATE REGARDING MACROECONOMIC CONDITIONS AND OTHER POTENTIAL DISRUPTIONS

Significant portions of our business are conducted in Europe, Asia and other international geographies. Factors such as global health outbreaks, adverse weather events, geopolitical events, tariffs, inflation, labor or raw material shortages and other supply chain disruptions could result in product shortages or other difficulties and delays or increased costs in manufacturing our products.

Economic conditions remain uncertain as markets continue to be impacted in part by elevated inflation, higher interest rates, extreme weather events, global supply chain uncertainties and risks associated with geopolitical conflicts. Global supply chain disruptions, such as strikes, work stoppages, port congestion, port closures, trade restrictions, capacity constraints and other logistical problems, may affect our ability to do business.

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 pharmaceutical ingredients, including finished drug products, medical countermeasures, critical inputs such as active pharmaceutical ingredients, key starting materials and derivative products of those items, under Section 232 of the Trade Expansion Act of 1962.

There is a high degree of uncertainty concerning what future steps countries and economic blocs will take in response to changes in global trade rules and economics.

We have significant manufacturing presence in the U.S. While our portfolio is evolving, approximately three quarters of our 2024 U.S. product revenue ~~comes~~was ~~from~~attributable to products ~~that~~which ~~are~~were ~~primarily~~largely manufactured ~~domestically~~in the U.S. However, we, and the pharmaceutical industry, do utilize partners and production facilities located outside the U.S. for certain raw materials, ingredients, processes and components for our pharmaceutical products and their delivery devices. Engaging alternative suppliers may involve seeking additional regulatory approvals and incurring additional costs and risks associated with new suppliers. This may be costly in terms of time and resources needed or result in delays.

Key products that are currently manufactured mainly outside the U.S. are TECFIDERA, VUMERITY and LEQEMBI. In 2024 we initiated a technology transfer process to enable us to manufacture LEQEMBI in the U.S.

Table of Contents

Although certain starting materials for SKYCLARYS rely on a single supplier based in China, the manufacturing process, including active pharmaceutical ingredients and drug substance, is primarily conducted in the U.S.

We are working to mitigate potential exposure from tariffs across our network.

We currently do not expect a material impact in 2025 from potential tariffs as previously announced by the U.S. Administration onduring ~~April 2,~~ 2025, even if the exemption for pharmaceuticals were to be removed. This is based on the expected timing of any potential tariffs, our manufacturing footprint, and our inventory levels and positioning, although the actual impact of tariffs on our business and financial condition may differ materially from our current expectations. We will continue to monitor the current and future global tariff landscape as it evolves.

Table of Contents

although the actual impact of tariffs on our business and financial condition may differ materially from our current expectations. We will continue to monitor the current and future global tariff landscape as it evolves.

GEOPOLITICAL TENSIONS

The ongoing geopolitical tensions related to Russia's invasion of Ukraine and the military conflict in the Middle East have resulted in global business disruptions and economic volatility. For example, sanctions and other restrictions have been levied on the government and businesses in Russia. Although we do not have affiliates or employees, in either Russia or Ukraine, we do provide various therapies to patients in Russia through a distributor. Government sanctions on the export of certain manufacturing materials to Russia may delay or limit our ability to get new products approved. The impact of the conflict on our operations and financial performance remains uncertain and will depend on future developments, including the severity and duration of the conflict between Russia and Ukraine, its impact on regional and global economic conditions and whether the conflict spreads or has effects on countries outside Ukraine and Russia.

We will continue to monitor the ongoing conflict between Russia and Ukraine as well as the military conflict in the Middle East and assess any potential impacts on our business, supply chain, partners or customers, as well as any factors that could have an adverse effect on our results of operations. Revenue generated from sales in Russia and Ukraine represent less than 1.0% of total revenue for the three and ~~six~~nine months ended ~~June~~September 30, 2025 and 2024. Additionally, revenue generated from sales in the Middle East region represents less than 2.0% of total revenue for the three and ~~six~~nine months ended ~~June~~September 30, 2025 and 2024.

INFLATION REDUCTION ACT OF 2022

In August 2022 the IRA was signed into law in the U.S. The IRA introduced new tax provisions, including a 15.0% corporate alternative minimum tax and a 1.0% excise tax on stock repurchases. The provisions of the IRA are effective for periods after December 31, 2022. The IRA did not result in any material adjustments to our income tax provision for the three and ~~six~~nine months ended ~~June~~September 30, 2025 and 2024. Preliminary guidance has been issued by the IRS and we expect additional guidance and regulations to be issued in future periods. We continue to assess its potential impact on our business and results of operations as further information becomes available.

The IRA also contains substantial drug pricing reforms that may have a significant impact on the pharmaceutical industry in the U.S. This includes the following:

(i) allowing CMS to negotiate prices for select high-cost Medicare Part D drugs (beginning in 2026) and Part B drugs (beginning in 2028) to reduce out-of-pocket prescription drug costs for beneficiaries, potentially resulting in higher contributions from plans and manufacturers;

(ii) drug inflationary rebate requirements to penalize manufacturers from raising the prices of Medicare covered single-source drugs and biologics beyond the inflation-adjusted rate, beginning in 2022 for Part D drugs and 2023 for Part B drugs;

(iii) to incentivize biosimilar development, the IRA provides an 8.0% Medicare Part B add-on payment for qualifying biosimilar products for a five-year period; and

(iv) Medicare Part D redesign which replaces the current coverage gap provisions and establishes a $2,000 cap for out-of-pocket costs for Medicare beneficiaries beginning in 2025, with manufacturers being responsible for up to 10.0% of costs up to the $2,000 cap and up to 20.0% after that cap is reached. Manufacturers that qualify as either specified or specified small manufacturers will phase-in the new manufacturer liability for prescription drug costs over a 7-year period from 2025 to 2031 for certain Medicare Part D drugs dispensed to certain beneficiaries. In April 2024 CMS informed us that we qualified for the specified manufacturer exception pertaining to the Medicare Part D redesign.

We expect the IRA's drug pricing controls and Medicare Part D redesign may have an adverse impact on our full-year sales, particularly for our products that are more substantially reliant on Medicare reimbursement. We anticipate the IRA Medicare Part D redesign will have a modest net unfavorable impact to our 2025 revenue, ranging from approximately $50.0 million to $100.0 million, concentrated in our SKYCLARYS and MS portfolio product revenue, approximately a third of which could be associated with SKYCLARYS.

The degree of impact from this legislation on our business depends on a number of forthcoming implementation actions by regulatory authorities, which may be further impacted by other legislative acts that may modify or replace the IRA, such as the OBBBA, as discussed below. The full extent of the IRA's impacts on our sales and, in turn, our business, remains uncertain.57

Table of Contents

2025 LEGISLATION AND TAX REFORM

On July 4, 2025, the U.S. signed into law the H.R.1 legislation formally titled "An Act to Provide for Reconciliation Pursuant to Title II of H. Con. Res. 14", commonly referred to as the OBBBA.

~~Based~~The onOBBBA did not result in any material adjustments to our ~~initial~~total ~~assessment~~income oftax provision for the ~~OBBBA,~~three weand donine ~~not~~months ~~expect~~ended ~~the~~September ~~introduced~~30, ~~tax~~2025, ~~changes~~and towe have aadjusted ~~material~~our ~~impact~~deferred ontax ~~our~~balances ~~consolidated~~to ~~financial~~reflect ~~statements~~the inimpacts ~~2025~~of the OBBBA enactment. However, given the complexity of tax laws, related regulations and interpretations, our current estimates may require revision as additional information becomes available regarding the application of the OBBBA provisions.

The OBBBA also enacts significant potential changes to Medicaid funding and rescinds or does not continue elements of the PPACA. The OBBBA implements additional eligibility rules on government health plans, expands administrative procedures around enrollment, modifies how states can obtain federal funding for Medicaid and no longer extends ACA premium subsidies. Additional federal and state guidance is expected to be issued in order to implement these OBBBA provisions, most of which have effective dates in 2027 and 2028.

At this time, we are unable to determine the overall impact that the OBBBA will have on our business, results of operations and financial condition, or the impact the OBBBA will have on the pharmaceutical industry as a whole because any such impact will depend upon developing interpretations of the OBBBA provisions and implementing regulations, which may be material.

5458

Table of Contents

FINANCIAL HIGHLIGHTS

As described below under Results of Operations, our net income and diluted earnings per share attributable to Biogen Inc. for the three months ended ~~June~~September 30, 2025, compared to the three months ended ~~June~~September 30, 2024, reflects the following:


TOTAL REVENUE

Increased

$~~180~~68.69 million or 72.38%


DILUTED EARNINGS PER SHARE

Increased

$0.3351 or 819.32%


PRODUCT REVENUE, NET

Decreased

$20.9 million or 1.1%

•MS revenue decreased $42.6 million, or 3.7%

•Rare disease revenue increased $8.9 million, or 1.7%

•The decrease in MS product revenue was primarily due to a decrease in global TECFIDERA and TYSABRI demand due to increased competition outside the U.S. from generic and biosimilar competition, respectively. These factors were offset in part by an increase in demand for U.S. VUMERITY and favorable U.S. TYSABRI inventory dynamics. MS product revenue in the U.S. also benefited from favorable commercial mix and approximately $45.0 million of favorable changes in estimates resulting in lower discounts and allowances.

•The increase in rare disease product revenue was primarily due to our new product launches, including global SKYCLARYS revenue of $130.3 million and global QALSODY revenue of $20.0 million in the second quarter of 2025.

TOTAL COST AND EXPENSE

Increased

$~~135~~77.35 million or 74.74%

•~~Cost~~MS ofrevenue ~~sales~~ increased $597.06 million, or 100.87%

•~~R&D~~Rare ~~expense~~disease ~~decreased~~revenue increased $~~106~~38.45 million, or 217.18%

•~~Acquired~~The ~~IPR&D~~increase in MS product revenue was primarily due to an increase in U.S. VUMERITY driven by higher demand, ~~upfront~~timing of shipments and ~~milestone~~favorable ~~expense~~pricing dynamics, partially offset by a decrease in global TECFIDERA demand due to increased competition outside the U.S. from generic competition. MS product revenue in the U.S. also benefited from favorable commercial mix and approximately $38.1 0 million of favorable changes in estimates from discounts and allowances.

•~~SG&A~~The ~~expense~~increase ~~increased~~in rare disease product revenue was primarily due to our new product launches, including global SKYCLARYS revenue of $30132.09 million, orand 5global QALSODY revenue of $26.4% million in the third quarter of 2025.

•~~The~~ZURZUVAE ~~increase~~revenue ~~in cost~~ of ~~sales~~$55.3 ~~was~~million ~~primarily~~in ~~due~~the tothird ~~higher~~quarter ~~contract~~of ~~manufacturing~~2025 ~~revenue~~was ~~and~~driven ~~higher SKYCLARYS amortization costs, partially offset~~ by ~~lower~~the ~~inventory~~continued ~~write-offs~~launch in the ~~second quarter of 2025~~U.S.


TOTAL COST AND EXPENSE

Decreased

$37.4 million or 1.9%

•Cost of sales increased $35.7 million, or 5.6%

•R&D expense decreased $80.1 million, or 15.5%

•SG&A expense increased $6.4 million, or 1.1%

•The increase in cost of sales was primarily due to a charge recorded during the third quarter of 2025 of approximately $104.3 million related to a litigation matter and higher SKYCLARYS inventory step-up amortization costs, partially offset by lower cost of contract manufacturing revenue driven by the timing of batch releases and lower inventory write-offs during the third quarter of 2025.

•The decrease in R&D expense was primarily driven by continued cost reduction measures realized in connection with our portfolio prioritization initiatives and our Fit for Growth program, offset in part by higher spend on clinical trials, including litifilimab and felzartamab. Higher clinical trial spend related to litifilimab was offset by $50.0 million in R&D funding received from Royalty Pharma.

•The increase in ~~acquired IPR~~SG&D,A ~~upfront and milestone~~ expense was primarily due to anincreases ~~upfront~~in ~~payment~~operational ofspending ~~$16.0 million~~on tosales ~~City~~and ~~Therapeutics~~marketing activities in ~~connection~~support ~~with the closing~~ of ~~our~~LEQEMBI ~~strategic~~and ~~research~~SKYCLARYS ~~arrangement,~~ as ~~well~~we ascontinue ato ~~$30.0 million~~expand ~~milestone~~our ~~accrued~~U.S. ~~during~~and ~~the~~international ~~second~~product ~~quarter of 2025 in connection with the first patient dosed in a Phase 3 clinical trial of felzartamab for the treatment of IgAN~~launches.

•The increase in SG&A expense was primarily due to an increase in operational spending on sales and marketing activities in support of LEQEMBI and SKYCLARYS as we continue to expand our U.S. and international product launches.


FINANCIAL CONDITION, LIQUIDITY AND CAPITAL RESOURCES

•Cash, ~~and~~ cash equivalents and marketable securities totaled approximately $24.80 billion as of ~~June~~September 30, 2025, compared to approximately $2.4 billion as of December 31, 2024.

•We generated approximately $~~420~~1.27 ~~million~~billion of net cash flow from operations for the ~~six~~nine months ended ~~June~~September 30, 2025, compared to approximately $~~1,179~~2.01 ~~million~~billion in the prior year comparative period.

•~~This~~The year-over-year reduction in net cash flow from operations was due in part to higher worldwide tax payments in 2025, ~~compared to 2024,~~ of approximately $~~774~~840.7 million ~~due~~driven toby the timing of estimated payments.

•In May 2025 we issued our 2025 Senior Notes for an aggregate principal amount of $1.75 billion. In June 2025 we used the net proceeds to redeem our 4.050% Senior Notes due September 15, 2025, prior to maturity.

5559

Table of Contents

RECENT DEVELOPMENTS

~~CORPORATE~~2025 ~~MATTERS~~ACQUISITIONS, COLLABORATIVE AND OTHER RELATIONSHIPS

~~2025~~ALCYONE ~~SENIOR~~THERAPEUTICS, ~~NOTES~~INC.

OnIn ~~May~~September ~~12,~~ 2025, we ~~issued~~entered ~~our~~into ~~2025~~a ~~Senior~~definitive ~~Notes~~agreement ~~for~~to anacquire ~~aggregate~~all ~~principal~~of ~~amount~~the issued and outstanding shares of $1Alcyone Therapeutics, Inc.~~75 billion~~, a clinical-stage biotechnology company focused on pediatric care through precision CNS therapeutics and dosing platforms. InAlcyone's ~~June~~lead ~~2025~~asset weis ~~used~~ThecaFlex ~~the~~DRx, ~~net~~an ~~proceeds~~implantable ~~from~~subcutaneous port and catheter device being investigated for the ~~sale~~intrathecal delivery of ~~our~~ASOs, ~~2025~~which ~~Senior~~is ~~Notes~~designed to ~~redeem~~provide ~~our~~an ~~4.050%~~alternative ~~Senior~~to ~~Notes~~repeat ~~due~~lumbar ~~September~~punctures ~~15,~~in ~~2025,~~chronic ~~prior~~intrathecal toadministration ~~maturity~~of medicines.

~~For~~We ~~additional~~have ~~information~~agreed ~~relating~~ to ~~our~~pay ~~2025~~an ~~Senior~~upfront ~~Notes,~~cash ~~please~~payment ~~read~~of ~~Note~~$85.0 million ~~13,~~upon ~~Indebtedness~~closing, plus additional potential amounts payable upon the achievement of certain milestones related to ~~our~~the ~~condensed~~development ~~consolidated~~and ~~financial~~regulatory ~~statements~~approval ~~included~~of inThecaFlex ~~this~~DRx ~~report~~for administering SPINRAZA and additional pipeline products.

~~NEW~~We ~~CORPORATE~~plan ~~HEADQUARTERS~~to ~~LEASE~~account for this proposed acquisition as an asset acquisition as the value being acquired primarily relates to a single asset and plan to record the upfront payment within acquired in-process research and development, upfront and milestone expense within our condensed consolidated statements of income upon the completion of this proposed acquisition. We anticipate the proposed acquisition to close during the fourth quarter of 2025, subject to the satisfaction of customary closing conditions. Under the terms of this proposed acquisition, we expect to oversee the end-to-end development, manufacturing and commercialization of ThecaFlex DRx.

InAlcyone's ~~March~~remaining ~~2025~~therapeutic weassets ~~entered~~would 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~~divested asfrom ~~our~~Alcyone ~~new~~into ~~global~~Neela ~~corporate headquarters~~Therapeutics, ~~as well as integrating our research and development and technical operations teams alongside our North American commercial organization~~Inc., ~~As part of~~ a ~~multi-year~~newly ~~real~~formed ~~estate~~independent ~~consolidation~~company, ~~plan~~prior ~~that is expected~~ to ~~result~~the inclosing ~~a reduction~~ of ~~approximately 40% in our real estate footprint in Massachusetts,~~ this ~~new~~proposed ~~lease~~acquisition. isWe ~~intended~~anticipate to ~~replace~~make ~~two~~a ~~existing~~convertible ~~leases,~~debt ~~both~~investment inof ~~Cambridge,~~up ~~Massachusetts,~~to ~~including our current corporate headquarters~~$5.0 million Wein ~~expect~~Neela ~~the initial lease term of approximately 15~~Therapeutics.5 ~~years to commence on May 31, 2028~~Inc.

For additional information on our ~~lease~~proposed ~~agreement~~acquisition of Alcyone, please read Note 122, ~~Leases~~Acquisitions, to our condensed consolidated financial statements included in this report.

COLLABORATIVE AND OTHER RELATIONSHIPS

CITY THERAPEUTICS, INC. COLLABORATION

For additional information on our strategic research arrangement with City Therapeutics, please read Note 19, Collaborative and Other Relationships, to our condensed consolidated financial statements included in this report.

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 isdosed aits ~~Phase~~first ~~3-ready~~patient ~~disease~~in ~~modifying~~August ~~asset~~2025, onadvancing ~~track~~zorevunersen to ~~start dosing in~~ a global Phase 3 ~~registrational study in the third quarter of 2025~~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.

Table of Contents

For additional information on our collaboration arrangement with Stoke, please read Note 19, Collaborative and Other Relationships, to our condensed 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 will receive up to $200.0 million in 2025 and 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. We plan to recognize this funding as a reduction to research and development expense within our condensed consolidated statements of income, proportionate to the related expense. For the three and ~~six~~nine months ended ~~June~~September 30, 2025, we recorded reductions to research and development expense of $50.0 million and $~~100~~150.0 million, respectively, within our condensed consolidated statements of income.

For additional information on our funding arrangement with Royalty Pharma, please read Note 19, Collaborative and Other Relationships, to our condensed 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 August 2025 the FDA approved the BLA for LEQEMBI subcutaneous autoinjector (IQLIK) for weekly maintenance dosing.

•In January 2025 the FDA approved LEQEMBI monthly IV maintenance dosing for the treatment of early Alzheimer's disease.

•In January 2025 the FDA accepted for review the BLA for LEQEMBI subcutaneous autoinjector for weekly maintenance dosing, with a PDUFA action date set for August 31, 2025.

Rest of World

Key developments related to LEQEMBI (lecanemab) in rest of world markets consisted of the following:

•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.

Table of Contents

•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.

•In March 2025 we and Eisai announced that the Therapeutic Goods Administration of Australia confirmed the initial decision made in October 2024 to decline the approval of lecanemab as a treatment for early Alzheimer's disease.

ZURZUVAE (zuranolone)

•In ~~July~~September 2025 the ~~CHMP~~EC ofapproved ~~the~~ZURZUVAE ~~EMA~~in ~~adopted~~the aE.U. ~~positive~~for ~~opinion~~the ~~recommending~~treatment ~~the~~of ~~marketing~~PPD ~~authorization~~in ~~for~~adults ~~zuranolone~~following ~~for~~childbirth, offering the first and only treatment ofindicated for PPD in the E.U.

57•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.

~~Table~~SALANERSEN ~~of Contents~~(BIIB115)

•In June 2025 we announced positive 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. We are currently engaging with regulators about the possibility of advancing salanersen to a Phase 3 registrational study.

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 accrued a $30.0 million milestone payment to MorphoSys, which was subsequently paid 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 late 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~~September 2025 the FDA ~~accepted~~issued ~~the~~a ~~supplemental~~CRL ~~NDA~~for ~~and~~ the ~~EMA~~supplemental ~~validated~~NDA ~~the application~~ for a higher dose regimen of nusinersen for the treatment of SMA. The ~~higher~~CRL ~~dose~~requested ~~regimen~~an ofupdate ~~nusinersen~~to ~~comprises~~the atechnical ~~more~~information ~~rapid~~to ~~loading~~be ~~regimen,~~included ~~two~~in 50the ~~mg-doses~~Chemistry 14Manufacturing ~~days~~and ~~apart,~~Controls module of the supplemental NDA and ~~higher~~did ~~maintenance~~not cite any deficiencies in the clinical data of the high dose regimen,. 28The ~~mg,~~CRL ~~every~~provided ~~four~~options ~~months,~~for ~~compared~~resolution and we have announced a plan to resubmit the ~~currently~~application ~~approved~~promptly ~~dose~~based ofupon ~~SPINRAZA~~readily available information.

~~SALANERSEN~~•In ~~(BIIB115)~~January 2025 the FDA accepted for review the supplemental NDA and the EMA validated the application for a higher dose regimen of nusinersen for SMA. The higher dose regimen of nusinersen comprises a more rapid loading regimen, two 50 mg-doses 14 days apart, and higher maintenance regimen, 28 mg, every four months, compared to the currently approved dose of SPINRAZA.

In June 2025 we announced positive 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. We are currently engaging with regulators to advance salanersen to a Phase 3 registrational study.

SKYCLARYS (omaveloxolone)

•In June 2025 we announced the initiation of dosing in the global Phase 3 BRAVE study. This study will evaluate the efficacy and safety of omaveloxolone in children with FA between the ages of two and sixteen years old.

•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 ~~March~~July 2025 ~~Health~~the ~~Canada~~Medicines ~~issued~~and ~~marketing~~Healthcare ~~authorization~~products ~~with~~Regulatory ~~conditions~~Agency ~~for~~in the U.K. approved 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.~~

•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.

Table of Contents

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.

DISCONTINUED PROGRAMS AND STUDIES

SALE OF TOFIDENCE

58For additional information on our sale of TOFIDENCE, please read Note 3, Dispositions, to our condensed consolidated financial statements included in this report.

CORPORATE MATTERS

2025 SENIOR NOTES

On May 12, 2025, we issued our 2025 Senior 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 condensed consolidated financial statements included in this report.

NEW CORPORATE HEADQUARTERS LEASE

For additional information on our lease agreement, please read Note 12, Leases, to our condensed consolidated financial statements included in this report.

Table of Contents

RESULTS OF OPERATIONS

REVENUE

The following revenue discussion should be read in conjunction with Note 5, Revenue, to our condensed consolidated financial statements included in this report. Revenue is summarized as follows:

	For the Three Months Ended June 30,
	For the Three Months Ended September 30,
(In millions, except percentages)	2025				2024				$ Change		% Change
Product revenue, net:
United States	$	~~941~~935.13	3536.69	%	$	~~846~~813.70	3433.40	%	$	94122.43	1115.10	%
Rest of world	~~937~~911.6		3536.40		~~1,052~~956.94		4238.78		(~~115~~44.38)		(114.07)
Total product revenue, net	1,~~878~~846.79		7172.09		1,~~899~~769.64		7771.18		~~(20~~77.9)5		(14.1)4
Revenue from anti-CD20 therapeutic programs	~~467~~493.39		1719.74		~~444~~446.52		18.01		2247.87		510.17
Alzheimer's collaboration revenue(1)	5442.97		2.1.7		1118.86		0.58		4324.1		~~365~~129.36
Contract manufacturing, royalty and other revenue	~~244~~151.62		96.20		~~109~~231.06		49.43		~~135~~(80.64)		~~124~~(34.47)
Total revenue	$	2,~~645~~534.57	100.0	%	$	2,~~464~~465.98	100.0	%	$	~~180~~68.69	72.38	%
	For the Six Months Ended June 30,
	For the Nine Months Ended September 30,
(In millions, except percentages)	2025				2024				$ Change		% Change
Product revenue, net:
United States	$	12,~~694~~630.92	3334.45	%	$	12,~~592~~405.8	33.53	%	$	~~102~~224.14	69.43	%
Rest of world	12,~~910~~821.39		37.61		2,~~018~~975.71		4241.52		(~~108~~153.42)		(5.41)
Total product revenue, net	35,~~605~~452.21		71.06		35,~~611~~380.59		7674.05		(671.3)2		(01.2)3
Revenue from anti-CD20 therapeutic programs	~~845~~1,339.54		1617.76		~~838~~1,284.57		17.68		754.07		04.83
Alzheimer's collaboration revenue(1)	87130.96		1.7		1433.62		0.35		7397.34		~~502~~293.14
Contract manufacturing, royalty and other revenue	~~537~~689.91		109.61		~~290~~522.84		67.12		~~247~~166.17		8531.09
Total revenue	$	57,~~076~~611.52	100.0	%	$	47,~~755~~221.42	100.0	%	$	~~321~~390.10	65.84	%

(1) Alzheimer's collaboration revenue consists of our 50.0% share of LEQEMBI product revenue, net and cost of sales, including royalties.

PRODUCT REVENUE

Product revenue is summarized as follows:

	For the Three Months Ended June 30,
	For the Three Months Ended September 30,
	2025								2024
(In millions, except percentages)	UnitedStates		Rest ofWorld		Total		%Total		UnitedStates		Rest ofWorld		Total		%Total		$Change		% Change
Multiple Sclerosis	$	~~657~~642.49	$	~~449~~418.86	$	1,~~107~~061.25	5857.95	%	$	~~582~~546.40	$	~~567~~507.49	$	1,~~149~~053.89	6059.56	%	$	~~(42~~7.6)	(30.7)	%
Rare Disease	~~234~~235.81		~~308~~298.2		~~543~~533.03		28.9		~~237~~240.54		~~296~~254.64		~~534~~494.18		28.10		838.95		1.7.8
Biosimilars	2.50		~~179~~194.28		~~181~~196.78		910.76		114.13		~~187~~192.03		~~198~~196.16		1011.51		~~(16~~0.4)2		(80.3)1
Other(1)	4655.43		~~0.4~~—		4655.83		23.50		1522.73		1.98		1724.61		01.93		2931.2		~~165~~129.95
Total product revenue, net	$	~~941~~935.13	$	~~937~~911.6	$	1,~~878~~846.79	100.0	%	$	~~846~~813.70	$	~~1,052~~956.94	$	1,~~899~~769.64	100.0	%	$	~~(20~~77.9)5	(14.1)4	%
	For the Six Months Ended June 30,
	For the Nine Months Ended September 30,
	2025								2024
(In millions, except percentages)	UnitedStates		Rest ofWorld		Total		%Total		UnitedStates		Rest ofWorld		Total		%Total		$Change		% Change
Multiple Sclerosis	$	1,~~147~~790.87	$	~~912~~1,331.40	$	23,~~060~~121.27	57.12	%	$	1,~~085~~631.6	$	1,~~140~~648.10	$	23,~~225~~279.76	6160.69	%	$	(~~165~~157.59)	(7.4.8)	%
Rare Disease	~~465~~700.89		~~640~~938.57		1,~~106~~639.36		30.71		~~463~~703.48		~~494~~749.60		~~958~~1,452.08		2627.50		~~148~~186.38		1512.59
Biosimilars	68.8		~~355~~550.75		~~362~~559.53		10.13		1419.81		~~380~~572.25		~~395~~591.06		11.0		(32.53)		(85.25)
Other(1)	74129.58		1.7		76131.25		2.14		2951.03		35.86		3256.89		01.91		4374.46		~~132~~131.31
Total product revenue, net	$	12,~~694~~630.92	$	12,~~910~~821.39	$	35,~~605~~452.21	100.0	%	$	12,~~592~~405.8	$	2,~~018~~975.71	$	35,~~611~~380.59	100.0	%	$	(671.3)2	(01.2)3	%

(1) Other includes ZURZUVAE, FUMADERM and ADUHELM.

5964

Table of Contents


MULTIPLE SCLEROSIS

•Global ~~TYSABRI~~VUMERITY revenue ~~decreased~~increased $756.65 million, from $~~462~~158.21 million in 2024 to $~~454~~214.6 million in 2025, or 135.67%, primarily due to ~~increased~~an ~~competition,~~increase ~~including the impacts from a biosimilar entrant of TYSABRI~~ in ~~Europe~~U.S. ~~The~~VUMERITY ~~decrease~~driven ~~was~~by ~~partially~~higher ~~offset~~demand, bytiming anof ~~increase~~shipments inand ~~U.S.~~favorable ~~TYSABRI~~pricing ~~driven~~dynamics, byas well as a favorable change in estimate of approximately $1213.0 million related to rebates and discounts ~~and~~in ~~favorable~~the ~~inventory dynamics~~U.S.

•Global ~~TECFIDERA~~TYSABRI revenue ~~decreased~~increased $5825.67 million, from $~~252~~406.21 million in 2024 to $~~193~~431.68 million in 2025, or 236.23%, ~~driven~~primarily due to higher net pricing in the U.S. and a favorable change in estimate related to rebates and discounts in the U.S., partially offset by a decrease in global TYSABRI demand ~~resulting~~due to increased competition, including the impacts from ~~multiple~~a ~~TECFIDERA~~biosimilar ~~generic~~entrant ~~entrants~~of TYSABRI in Europe.

•Global Interferon revenue ~~decreased~~increased $49.24 million, from $~~250~~237.95 million in 2024 to $246.79 million in 2025, or 14.70%, asprimarily ~~patients~~due ~~continue~~ to ~~transition~~a favorable change in estimate of approximately $18.0 million related to ~~higher~~rebates ~~efficacy~~and ~~therapies~~discounts. This ~~decline~~increase iswas partially offset by ~~favorable~~a ~~inventory~~decrease ~~dynamics~~ in ~~the~~rest Uof world Interferon revenue as patients continue to transition to higher efficacy therapies.S.

•Global ~~VUMERITY~~TECFIDERA revenue ~~increased~~decreased $4664.56 million, from $~~165~~232.8 million in 2024 to $~~212~~168.32 million in 2025, or 2827.07%, ~~primarily~~driven ~~due~~by ~~to favorable commercial mix and~~ a ~~favorable~~decrease ~~change~~ in ~~estimate~~demand ofresulting ~~approximately~~from ~~$22.0~~multiple ~~million~~TECFIDERA ~~related~~generic ~~to rebates and discounts, partially offset by charges related to the IRA~~entrants.

•Global ~~TYSABRI~~VUMERITY revenue ~~decreased~~increased $57114.43 million, from $~~893~~451.54 million in 2024 to $~~836~~565.17 million in 2025, or 625.43%, primarily due to aan ~~decrease~~increase in U.S. VUMERITY driven by higher demand and ~~pricing~~a favorable change in ~~rest~~estimate of ~~world~~approximately ~~TYSABRI,~~$40.0 million ~~offset~~related into ~~part~~rebates byand ~~favorable~~discounts ~~net pricing~~ in the U.S., partially offset by charges related to the IRA redesign.

•Global ~~TECFIDERA~~TYSABRI revenue decreased $~~106~~31.87 million, from $~~506~~1,299.56 million in 2024 to $~~399~~1,267.79 million in 2025, or 212.14%, ~~driven~~primarily bydue to increased competition in rest of world, including the impacts from a ~~decrease~~biosimilar entrant of TYSABRI in ~~demand~~Europe. asThe decrease was partially offset by a ~~result~~favorable change in estimate of ~~multiple~~approximately ~~TECFIDERA~~$16.0 million ~~generic~~related ~~entrants~~to rebates and discounts and favorable inventory dynamics in the U.S.

•Global Interferon revenue decreased $2112.51 million, from $~~494~~732.50 million in 2024 to $~~473~~719.09 million in 2025, or 41.37%, driven by a decrease in demand as patients transition to higher efficacy therapies, offset in part by a favorable change in estimate of approximately $32.0 million related to rebates and disco

Filing Compare · BIOGEN INC.