FMR LLC reports 16.65M Biogen shares (11.3%)

Biogen Inc. ownership amendment: FMR LLC reports beneficial ownership of 16,652,974.82 shares of Common Stock, equal to 11.3% of the class.

Rhea-AI Filing Summary

Biogen Inc. ownership amendment: FMR LLC reports beneficial ownership of 16,652,974.82 shares of Common Stock, equal to 11.3% of the class. The filing lists sole voting power of 15,060,090.91 shares and sole dispositive power of 16,652,974.82. The schedule is an amendment signed on 06/04/2026 and references an Exhibit 99 13d-1(k)(1) agreement.

Insights

Institutional Ownership Analyst

FMR LLC reports an 11.3% stake in Biogen, showing substantial passive ownership.

FMR LLC's Schedule 13G/A lists 16,652,974.82 shares beneficially owned with 15,060,090.91 shares of sole voting power. The filing is presented as an amendment and cites an Exhibit 99 agreement.

The holding is reported as passive under the 13G/A process; any material change in voting or disposition rights would require updated disclosure in subsequent schedules or amendments.

Securities Compliance Specialist

Amendment and referenced exhibit indicate procedural updates, not an active change in control.

The schedule clarifies ownership and powers: sole dispositive power is 16,652,974.82 shares and shared powers are 0.00. The signature block shows authorization by a power of attorney.

Regulatory watchers should note the reference to the 13d-1(k)(1) agreement in Exhibit 99; subsequent filings would disclose any shift from passive to active intent.

Key Figures

Beneficially owned: 16,652,974.82 shares Percent of class: 11.3% Sole voting power: 15,060,090.91 shares +3 more

6 metrics

Beneficially owned 16,652,974.82 shares Amount beneficially owned reported on Schedule 13G/A

Percent of class 11.3% Percent of Common Stock reported in Item 4

Sole voting power 15,060,090.91 shares Sole power to vote reported on the cover page

Sole dispositive power 16,652,974.82 shares Sole power to dispose reported in Item 4

Signature date 06/04/2026 Date signatures were provided on the amendment

CUSIP 09062X103 Issuer CUSIP listed on the cover

Key Terms

Schedule 13G/A, beneficial ownership, sole dispositive power, 13d-1(k)(1) agreement

4 terms

Schedule 13G/A regulatory

"Item 1 shows this is a Schedule 13G/A filing"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

beneficial ownership regulatory

"Item 4(a) states Amount beneficially owned: 16652974.82"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

sole dispositive power regulatory

"Cover page lists Sole Dispositive Power 16,652,974.82"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

13d-1(k)(1) agreement regulatory

"Exhibit Information references Exhibit 99 for 13d-1(k)(1) agreement"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What stake does FMR LLC report in Biogen (BIIB)?

FMR LLC reports beneficial ownership of 16,652,974.82 shares, representing 11.3% of Biogen's Common Stock. The filing lists sole voting power of 15,060,090.91 shares and sole dispositive power of 16,652,974.82.

Who filed the Schedule 13G/A for BIIB and when was it signed?

The Schedule 13G/A was filed by FMR LLC and includes authorization for Abigail P. Johnson. The signatures are dated 06/04/2026, and the cover references the issuer CUSIP 09062X103.

What does the filing say about voting and disposition powers?

The filing reports sole voting power of 15,060,090.91 shares and sole dispositive power of 16,652,974.82. Shared voting and dispositive powers are listed as 0.00 in the excerpt.

Does the filing indicate whether FMR LLC is acting on behalf of others?

The schedule states one or more other persons have rights to dividends or sale proceeds and that no other single person holds more than 5% of the class. It notes holdings include accounts or beneficiaries customary for investment managers.

What is Exhibit 99 referenced in the filing?

The filing references Exhibit 99 for a 13d-1(k)(1) agreement. That exhibit is cited as supporting identification/classification of the subsidiary or related agreement tied to this Schedule 13G/A.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 06/05/2026 - 10:13 AM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

BIOGEN INC

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

09062X103

(CUSIP Number)

05/29/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 09062X103

1

Names of Reporting Persons

FMR LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 15,060,090.91
6	Shared Voting Power 0.00
7	Sole Dispositive Power 16,652,974.82
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

16,652,974.82

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

11.3 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 09062X103

1

Names of Reporting Persons

Abigail P. Johnson

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 16,652,974.82
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

16,652,974.82

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

11.3 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: BIOGEN INC
(b)	Address of issuer's principal executive offices: 225 BINNEY STREET,Cambridge,MA,USA,02142
Item 2.
(a)	Name of person filing: FMR LLC
(b)	Address or principal business office or, if none, residence: 245 Summer Street, Boston, Massachusetts 02210
(c)	Citizenship: Not applicable
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP No.: 09062X103
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 16652974.82
(b)	Percent of class: 11.3 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Please see the responses to Items 5 and 6 on the cover page.
	(ii) Shared power to vote or to direct the vote: 0.00
	(iii) Sole power to dispose or to direct the disposition of: 16652974.82
	(iv) Shared power to dispose or to direct the disposition of: 0.00
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. One or more other persons are known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the COMMON STOCK of BIOGEN INC. No one other person's interest in the COMMON STOCK of BIOGEN INC is more than five percent of the total outstanding COMMON STOCK.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. See attached Exhibit 99.
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

FMR LLC

Signature:	Stephanie J. Brown
Name/Title:	Duly authorized under Power of Attorney effective as of January 3, 2023, by and on behalf of FMR LLC and its direct and indirect subsidiaries*
Date:	06/04/2026

Abigail P. Johnson

Signature:	Stephanie J. Brown
Name/Title:	Duly authorized under Power of Attorney effective as of January 26, 2023, by and on behalf of Abigail P. Johnson**
Date:	06/04/2026

Comments accompanying signature: * This power of attorney is incorporated herein by reference to Exhibit 24 to the Schedule 13G filed by FMR LLC on January 10, 2023, accession number: 0000315066-23-000003. ** This power of attorney is incorporated herein by reference to Exhibit 24 to the Schedule 13G filed by FMR LLC on January 31, 2023, accession number: 0000315066-23-000038.

Exhibit Information

Please see Exhibit 99 for 13d-1(k) (1) agreement.