Document Press Release Cambridge, Mass.

Cambridge, Mass. - February 6, 2026

Biogen reports strong fourth quarter and full year 2025 results and provides full year 2026 financial guidance

Fourth quarter 2025 total revenue $2.3 billion GAAP diluted EPS $(0.33) Non-GAAP diluted EPS $1.99

Full year 2025 total revenue $9.9 billion GAAP diluted EPS $8.79 Non-GAAP diluted EPS $15.28, exceeding the upper end of our 2025 full year guidance range of $14.50 to $15.00

Growth products1 up 6% year-over-year in the fourth quarter demonstrating continued strong commercial execution

LEQEMBI fourth quarter global in-market sales of approximately $134 million, up 54% year-over-year, with U.S. in-market sales of approximately $78 million, representing continued growth

SKYCLARYS grew global patients on therapy by approximately 30% in 2025 fourth quarter U.S. revenue of approximately $89 million driven by demand growth, with ex-U.S. revenue of approximately $44 million reflecting continued demand growth, also impacted by a one-time reimbursement true-up

ZURZUVAE fourth quarter revenue of approximately $66 million showed strong continued demand growth

VUMERITY grew 3% year-over-year in the fourth quarter

SPINRAZA fourth quarter revenue declined 15% year-over-year, impacted by timing of shipments outside the U.S., with full year revenue down 2% year-over-year

Full year 2025 revenue from growth products increased 19% year-over-year and offset the year-over-year revenue decline from multiple sclerosis products, excluding VUMERITY

Continued to deliver progress across key late-stage pipeline programs

LEQEMBI IQLIK subcutaneous treatment initiation granted FDA Priority Review with a PDUFA date of May 24, 2026 regulatory filings under review in Japan and China

FDA Breakthrough Therapy Designation granted for litifilimab in cutaneous lupus (CLE), a disease with no targeted treatment options both litifilimab Phase 3 systemic lupus (SLE) studies expected to read out in Q4 2026

High dose regimen of SPINRAZA approved in Japan and E.U. U.S. FDA PDUFA of April 3, 2026

BTK degrader (BIIB145) targeting autoimmune diseases Phase 1 study initiated in healthy volunteers

Full year 2026 financial guidance reflects continued business momentum and financial discipline

Full year 2026 Non-GAAP diluted EPS expected to be between $15.25 and $16.25

Expect full year 2026 total revenue to decline by a mid-single digit percentage versus full year 2025

Biogen Inc. (Nasdaq BIIB) today reported fourth quarter and full year 2025 financial results. Commenting on the results, President and Chief Executive Officer Christopher A. Viehbacher said

"Our 2025 performance reflected continued focus on strong execution and financial discipline, driven by our revenue of nearly $1 billion from LEQEMBI, SKYCLARYS, ZURZUVAE, and QALSODY, progression of our pipeline, and resilience of our MS franchise. Our pipeline momentum continues with a strong start in 2026, with the FDA recently granting Priority Review for LEQEMBI IQLIK initiation and Breakthrough Therapy Designation for litifilimab in CLE. These milestones highlight both the innovative and differentiated value of our medicines and the strength of our late-stage pipeline. Going into 2026, we are looking forward to data

1 Growth products include SKYCLARYS, QALSODY, ZURZUVAE, VUMERITY and SPINRAZA, plus Biogen's 50% share of net revenue and cost of sales, including royalties, from the LEQEMBI Collaboration.

from two Phase 3 studies in lupus for litifilimab, with 10 additional potentially registrational studies across our pipeline expected to read out sequentially over the next four years. This multi-year registrational data flow has the potential to drive meaningful innovation for patients and long-term value for shareholders."

Financial Highlights

Note Percent changes represented as favorable (unfavorable) versus the prior year period. N A not applicable.

* Percentage changes in revenue growth at constant currency (CC) are presented excluding the impact of changes in foreign currency exchange rates and hedging gains or losses. Foreign currency revenue values are converted into U.S. dollars using the exchange rates from the end of the previous calendar year.

A reconciliation of GAAP to Non-GAAP financial measures can be found in Table 4 at the end of this news release.

Note Percent changes represented as favorable (unfavorable) versus the prior year period. Numbers may not foot or recalculate due to rounding. NMF no meaningful figure.

(1) MS includes TECFIDERA , VUMERITY , AVONEX , PLEGRIDY , TYSABRI and FAMPYRA . Effective January 1, 2025, our collaboration and license agreement for FAMPYRA global commercialization rights was terminated.

(2) Rare disease includes SPINRAZA , SKYCLARYS and QALSODY .

(3) Other includes ZURZUVAE , ADUHELM and FUMADERM .

(4) Includes Biogen's 50% share of net revenue and cost of sales, including royalties, from the LEQEMBI Collaboration.

Note Percent changes represented as favorable (unfavorable) versus the prior year period.

IPR D in-process R D. NMF no meaningful figure.

*Excluding amortization and impairment of acquired intangible assets.

The decrease in fourth quarter 2025 GAAP and Non-GAAP cost of sales as a percentage of total revenue was driven primarily by favorable product mix including lower contract manufacturing revenue.

The increase in full year 2025 GAAP cost of sales as a percentage of total revenue was driven primarily by a pre-tax charge related to a judgment on Genentech's claim for past royalties and interest on sales of TYSABRI. The decrease in full year 2025 Non-GAAP cost of sales as a percentage of total revenue was driven primarily by favorable product mix.

The decrease in fourth quarter and full year 2025 GAAP and Non-GAAP R D expense was driven primarily by the favorable impact from the Company's Fit for Growth initiative and R D funding received, partially offset by increased investment in late-stage programs including felzartamab and litifilimab.

The increase in fourth quarter and full year 2025 GAAP and Non-GAAP SG A expense was driven primarily by sales and marketing spend to support product launches, partially offset by savings from the Company's Fit for Growth initiative.

Fourth quarter 2025 GAAP and Non-GAAP acquired IPR D, upfront and milestone expense was approximately $222 million.

Other Financial Highlights

Fourth quarter 2025 GAAP and Non-GAAP collaboration profit sharing was a net expense of approximately $70 million. This includes approximately $47 million related to Biogen's collaboration with Samsung Bioepis, and approximately $22 million related to Biogen's collaboration with Supernus Pharmaceuticals, Inc. related to the commercialization of ZURZUVAE in the U.S.

Full year 2025 GAAP and Non-GAAP collaboration profit sharing was a net expense of approximately $290 million. This includes approximately $219 million related to Biogen's collaboration with Samsung Bioepis, and approximately $71 million related to Biogen's collaboration with Supernus Pharmaceuticals, Inc. related to the commercialization of ZURZUVAE in the U.S.

Fourth quarter 2025 GAAP other expense was approximately $154 million and includes approximately $131 million related to litigation matters. Fourth quarter 2025 Non-GAAP other expense was approximately $46 million, primarily driven by net interest expense.

Full year 2025 GAAP other expense was approximately $306 million and includes the aforementioned approximately $131 million related to litigation matters. Full year 2025 Non-GAAP other expense was approximately $179 million, primarily driven by net interest expense.

Fourth quarter 2025 GAAP and Non-GAAP effective tax rates were 12.8% and 10.1%, respectively. Fourth quarter 2024 GAAP and Non-GAAP effective tax rates were 8.5% and 12.2%, respectively.

Full year 2025 GAAP and Non-GAAP effective tax rates were 16.9% and 15.5%, respectively. Full year 2024 GAAP and Non-GAAP effective tax rates were 14.4% and 14.6%, respectively.

Fourth quarter 2025 net cash flow from operations was approximately $512 million. Capital expenditures were approximately $44 million, and free cash flow, defined as net cash flow from operations less capital expenditures, was approximately $468 million.

Full year 2025 net cash flow from operations was approximately $2.2 billion. Capital expenditures were approximately $154 million, and free cash flow, defined as net cash flow from operations less capital expenditures, was approximately $2.1 billion.

As of December 31, 2025, Biogen had cash and cash equivalents totaling approximately $4.2 billion with approximately $6.3 billion in total debt, resulting in net debt of approximately $2.0 billion.

For the fourth quarter of 2025 the Company's weighted average shares were 147 million and 148 million, used to calculate the Company's GAAP and Non-GAAP diluted EPS, respectively. All unvested equity-based awards are antidilutive for GAAP due to reporting a net loss for the fourth quarter of 2025. For full year 2025 the Company's weighted average diluted shares were 147 million.

Full Year 2026 Financial Guidance

For the full year 2026, Biogen expects a Non-GAAP diluted EPS guidance range as follows

Total revenue is expected to decline by a mid-single digit percentage for 2026 as compared to 2025 as further declines in multiple sclerosis product revenue, excluding VUMERITY, are expected to be partially offset by increases in revenue from growth products.

For full year 2026 as compared to full year 2025, Biogen expects the gross margin percentage, and combined Non-GAAP R D expense and Non-GAAP SG A expense to be roughly consistent year-over-year. Biogen expects full year 2026 Non-GAAP effective tax rate to be between approximately 17% and 18%.

This guidance also assumes that foreign exchange rates as of January 30, 2026, will remain in effect for the remainder of the year, net of hedging activities.

Unless expressly stated above, this financial guidance does not include any acquired IPR D, impact from potential acquisitions or business development transactions or pending and future litigation or any impact of potential healthcare reform, as all are hard to predict. Other important financial considerations will be provided on the conference call and webcast.

Biogen may incur charges, realize gains or losses, or experience other events or circumstances in 2026 that could cause any of these assumptions and expectations to change and or actual results to vary from this financial guidance.

Biogen does not provide guidance for GAAP reported financial measures (other than revenue) or a reconciliation of forward-looking Non-GAAP financial measures to the most directly comparable GAAP reported financial measures because the Company is unable without unreasonable effort to predict with reasonable certainty the financial impact of items such as the transaction, integration, and certain other costs related to acquisitions or large business development transactions unusual gains and losses potential future asset impairments gains and losses from equity security investments and the ultimate outcome of pending or future litigation. These items are uncertain, depend on various factors, and could have a material impact on GAAP reported results for the guidance period. For the same reasons, the Company is unable to address the significance of the unavailable information, which could be material to future results.

Conference Call and Webcast

The Company's earnings conference call for the fourth quarter will be broadcast via the internet at 8 30 a.m. ET on February 6, 2026 and will be accessible through the Investors section of Biogen's website, www.biogen.com. Supplemental information in the form of a slide presentation is also accessible at the same location on the internet and will be subsequently available on the website for at least 90 days.

Founded in 1978, Biogen is a leading biotechnology company that pioneers innovative science to deliver new medicines to transform patient's lives and to create value for shareholders and our communities.

We apply deep understanding of human biology and leverage different modalities to advance first-in-class treatments or therapies that deliver superior outcomes. Our approach is to take bold risks, balanced with return on investment to deliver long-term growth.

This press release contains forward-looking statements, relating to our strategy and plans potential of, and expectations for, our commercial business and pipeline programs capital allocation and investment strategy clinical development programs, clinical trials, and data readouts and presentations regulatory discussions, submissions, filings, and approvals the potential benefits, safety, and efficacy of our and our collaboration partners' products and investigational therapies the anticipated benefits and potential of investments or acquisitions optimization of our cost structure including our Fit for Growth program the goal of creating long-term sustainable growth the impact from potential tariffs productivity of our R D pipeline, collaborations, and business development activities our future financial and operating results and our full year 2026 financial guidance. 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," "prospect," "should," "target," "will," "would," and other words and terms of similar meaning. Drug development and commercialization involve a high degree of risk, and only a small number of research and development programs result in commercialization of a product. Results in early-stage clinical trials may not be indicative of full results or results from later stage or larger scale clinical trials and do not ensure regulatory approval. You should not place undue reliance on these statements.

Given their forward-looking nature, these statements involve substantial risks and uncertainties that may be based on inaccurate assumptions and could cause actual results to differ materially from those reflected in such statements. 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 revenue from our products and other payments under licensing, collaboration, acquisition or divestiture agreements uncertainty of long-term success in developing, licensing, or acquiring other product candidates or additional indications for existing products expectations, plans, prospects and 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 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 our ability to effectively implement our corporate strategy the successful execution of our strategic and growth initiatives, including acquisitions the drivers for growing our business difficulties in obtaining and maintaining adequate coverage, pricing, and reimbursement for our products the drivers for growing our business, including our dependence on collaborators and other third parties for the development, regulatory approval, and commercialization of products and other aspects of our business, which are outside of our full control risks associated with current and potential future healthcare reforms risks related to commercialization of biosimilars, which is subject to such risks related to our reliance on third-parties, intellectual property, competitive and market challenges and regulatory compliance failure to obtain, protect, and enforce our data, intellectual property, and other proprietary rights and the risks and uncertainties relating to intellectual property claims and challenges the risk that positive results in a clinical trial may not be replicated in subsequent or confirmatory trials or success in early stage clinical trials may not be predictive of results in later stage or large scale

clinical trials or trials in other potential indications risks associated with clinical trials, including our ability to adequately manage clinical activities, unexpected concerns that may arise from additional data or analysis obtained during clinical trials, regulatory authorities may require additional information or further studies, or may fail to approve or may delay approval of our drug candidates the occurrence of adverse safety events, restrictions on use with our products, or product liability claims risks relating to technology, including our incorporation of new technologies such as artificial intelligence into some of our processes risks related to use of information technology systems and potential impacts of any breakdowns, interruptions, invasions, corruptions, data breaches, destructions and or other cybersecurity incidents of our systems or those of connected and or third-party systems problems with our manufacturing capacity, including our ability to manufacture products efficiently or adequately address global bulk supply risks risks relating to management, personnel and other organizational changes, including our ability to attracting, retaining and motivating qualified individuals risks related to the failure to comply with current and new legal and regulatory requirements, including judicial decisions, accounting standards, and tariff or trade restrictions the risks of doing business internationally, including geopolitical tensions, acts of war and large-scale crises risks relating to investment in our manufacturing capacity risks relating to the distribution and sale by third parties of counterfeit or unfit versions of our products risks relating to the use of social media for our business, results of operations and financial condition fluctuations in our operating results risks related to investment in properties risks relating to access to capital and credit markets to finance our present and future operations and business initiatives and obtain funding for such activities on favorable terms risks related to indebtedness the market, interest, and credit risks associated with our investment portfolio risks relating to share repurchase programs change in control provisions in certain of our collaboration agreements fluctuations in our effective tax rate and obligations in various jurisdictions in which we are subject to taxation environmental risks and any other risks and uncertainties that are described in other reports we have filed with the U.S. Securities and Exchange Commission which are available on the SEC's website at www.sec.gov.

These statements speak only as of the date of this press release and are based on information and estimates available to us at this time. Should known or unknown risks or uncertainties materialize or should underlying assumptions prove inaccurate, actual results could vary materially from past results and those anticipated, estimated or projected. Investors are cautioned not to put undue reliance on forward-looking statements. A further list and description of risks, uncertainties and other matters can be found in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024 and in our subsequent reports on Form 10-Q, in each case including in the sections thereof captioned "Note Regarding Forward-Looking Statements" and "Item 1A. Risk Factors," and in our subsequent reports on Form 8-K. Except as required by law, we do not undertake any obligation to publicly update any forward-looking statements whether as a result of any new information, future events, changed circumstances or otherwise.

Digital Media Disclosure

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 (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 webcasts, as the information posted on them could be material to investors.

BIOGEN INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME

(unaudited, in millions, except per share amounts)

BIOGEN INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited, in millions)

BIOGEN INC. AND SUBSIDIARIES

(unaudited, in millions)

(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.

BIOGEN INC. AND SUBSIDIARIES

(unaudited, in millions)

(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.

BIOGEN INC. AND SUBSIDIARIES

(unaudited, in millions)