BIIB

biib-202602060000875045false00008750452026-02-062026-02-06

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): February 6, 2026

BIOGEN INC.

(Exact name of registrant as specified in its charter)

Delaware0-1931133-0112644 (State or other jurisdiction of incorporation)(Commission File Number)(IRS Employer Identification No.)

225 Binney Street, Cambridge, Massachusetts 02142 (Address of principal executive offices; Zip Code)

Registrant’s telephone number, including area code: (617) 679-2000

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Title of each classTrading Symbol(s)Name of each exchange on which registered Common Stock, $0.0005 par valueBIIBThe Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

☐ 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. ☐

Item 2.02    Results of Operations and Financial Condition.

On February 6, 2026, Biogen Inc. issued a press release announcing its results of operations and financial condition for the fourth quarter and year ended December 31, 2025. A copy of the press release is furnished as Exhibit 99.1 and is incorporated herein by reference. The press release is being furnished pursuant to Item 2.02 of this Current Report on Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that Section, nor shall such document be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act. Item 9.01    Financial Statements and Exhibits.

(d)    Exhibits The exhibits listed below are furnished as part of this Current Report on Form 8-K.

Exhibit No.Description 99.1Biogen's press release dated February 6, 2026

104Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

BIOGEN INC.

By:    /s/ Wendell Taylor Wendell Taylor Secretary

Date: February 6, 2026

biib-202601130000875045false00008750452026-01-132026-01-13

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 13, 2026

Biogen Inc. (Exact name of registrant as specified in its charter)

Delaware0-1931133-0112644 (State or other jurisdiction of incorporation)(Commission File Number)(IRS Employer Identification No.)

225 Binney Street, Cambridge, Massachusetts 02142 (Address of principal executive offices; Zip Code)

Registrant’s telephone number, including area code: (617) 679-2000 Not Applicable (Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each classTrading Symbol(s)Name of each exchange on which registered Common Stock, $0.0005 par valueBIIBThe Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

☐ 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. ☐

Item 2.02     Results of Operations and Financial Condition Biogen Inc. (Biogen) expects that its GAAP and non-GAAP results for the fourth quarter of 2025 will include acquired in-process research and development, upfront and milestone expense of approximately $222 million on a pre-tax basis. The estimated charge is expected to impact GAAP and non-GAAP net income per diluted share for the fourth quarter 2025 by approximately $1.26 per share.

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. Biogen does not forecast such acquired in-process research and development, upfront and milestone expense due to the uncertainty of the future occurrence, magnitude and timing of these transactions in any given period.

Results for the quarter ended December 31, 2025, have not been finalized and are subject to our financial statement closing procedures. There can be no assurance that our final results will not differ from the preliminary unaudited estimates described herein.

Note Regarding Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking statements relating to our financial and operating results and financial guidance, 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 and could cause actual results to differ materially from those reflected in such statements. The information above includes, among others, forward-looking statements reflecting management’s current intentions and expectations for the future with respect to Biogen’s estimated acquired in-process research and development, upfront and milestone expense for the quarter ended December 31, 2025, and the related impact to Biogen’s GAAP and non-GAAP earnings per share for such period. These forward-looking statements are based on management's current beliefs and ass

biib-202510300000875045false00008750452025-10-302025-10-30

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 30, 2025

BIOGEN INC.

(Exact name of registrant as specified in its charter)

Delaware0-1931133-0112644 (State or other jurisdiction of incorporation)(Commission File Number)(IRS Employer Identification No.)

225 Binney Street, Cambridge, Massachusetts 02142 (Address of principal executive offices; Zip Code)

Registrant’s telephone number, including area code: (617) 679-2000

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Title of each classTrading Symbol(s)Name of each exchange on which registered Common Stock, $0.0005 par valueBIIBThe Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

☐ 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. ☐

Item 2.02    Results of Operations and Financial Condition.

On October 30, 2025, Biogen Inc. issued a press release announcing its results of operations and financial condition for the third quarter ended September 30, 2025. A copy of the press release is furnished as Exhibit 99.1 and is incorporated herein by reference. The press release is being furnished pursuant to Item 2.02 of this Current Report on Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that Section, nor shall such document be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act. Item 9.01    Financial Statements and Exhibits.

(d)    Exhibits The exhibits listed below are furnished as part of this Current Report on Form 8-K.

Exhibit No.Description 99.1Biogen's press release dated October 30, 2025

104Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

BIOGEN INC.

By:    /s/ Wendell Taylor Wendell Taylor Secretary

Date: October 30, 2025