FMR reports 12.4% beneficial stake in Biogen

FMR LLC and Abigail P. Johnson report beneficial ownership of 18,294,523.51 shares of Biogen Inc. common stock, representing 12.4% of the class.

Rhea-AI Filing Summary

FMR LLC and Abigail P. Johnson report beneficial ownership of 18,294,523.51 shares of Biogen Inc. common stock, representing 12.4% of the class. FMR LLC has sole voting power over 16,623,432.57 shares and sole dispositive power over all 18,294,523.51 shares.

Abigail P. Johnson reports sole dispositive power over the same 18,294,523.51 shares, with no voting power. One or more other persons may receive dividends or sale proceeds from these shares, but no single such person holds more than five percent of Biogen’s outstanding common stock.

Key Figures

Beneficial ownership: 18,294,523.51 shares Percent of class: 12.4 % Sole voting power (FMR LLC): 16,623,432.57 shares +3 more

6 metrics

Beneficial ownership 18,294,523.51 shares Biogen Inc common stock beneficially owned by FMR LLC and Abigail P. Johnson

Percent of class 12.4 % Portion of Biogen Inc common stock class reported as beneficially owned

Sole voting power (FMR LLC) 16,623,432.57 shares Biogen Inc shares over which FMR LLC has sole power to vote

Sole dispositive power (FMR LLC) 18,294,523.51 shares Biogen Inc shares over which FMR LLC has sole power to dispose

Sole dispositive power (Abigail P. Johnson) 18,294,523.51 shares Biogen Inc shares over which Abigail P. Johnson has sole dispositive power

Shared voting power 0.00 Biogen Inc shares with shared voting power reported by FMR LLC and Abigail P. Johnson

Key Terms

beneficially owned, sole voting power, sole dispositive power, percent of class, +2 more

6 terms

beneficially owned financial

"Item 4. | Ownership (a) | Amount beneficially owned: 18294523.51"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

sole voting power financial

"5 | Sole Voting Power 16,623,432.57 6 | Shared Voting Power 0.00"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

sole dispositive power financial

"7 | Sole Dispositive Power 18,294,523.51 8 | Shared Dispositive Power 0.00"

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.

percent of class financial

"Item 4. | Ownership (b) | Percent of class: 12.4 %"

Percent of class is the portion of a specific category of securities—such as a company’s common shares, preferred shares, or a bond series—that takes part in or approves a corporate action (vote, consent, tender, etc.). Investors watch this number because it reveals how much support or opposition exists within that particular shareholder group; like counting how many members of a club back a proposal, it can determine whether a plan passes or how influence is distributed.

Schedule 13G regulatory

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

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

parent holding company financial

"Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company"

FAQ

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

What percentage of Biogen Inc (BIIB) shares does FMR LLC report owning?

FMR LLC reports beneficial ownership of 12.4% of Biogen Inc. common stock, corresponding to 18,294,523.51 shares. This reflects a significant institutional position in Biogen, filed on a Schedule 13G/A as Amendment No. 3.

How many Biogen Inc (BIIB) shares does FMR LLC have voting power over?

FMR LLC has sole voting power over 16,623,432.57 shares of Biogen Inc. common stock. It reports no shared voting power and sole dispositive power over 18,294,523.51 shares, indicating broad control over how most of these shares are voted.

What is Abigail P. Johnson’s reported ownership in Biogen Inc (BIIB)?

Abigail P. Johnson reports beneficial ownership of 18,294,523.51 Biogen shares, or 12.4% of the common stock. She has sole dispositive power over these shares but reports no sole or shared voting power in this Schedule 13G/A filing.

Do other investors share in dividends or proceeds from FMR LLC’s Biogen Inc (BIIB) holdings?

Yes. One or more other persons may receive dividends or sale proceeds from the COMMON STOCK of Biogen Inc held by FMR-related entities. However, no single such person’s interest exceeds five percent of Biogen’s total outstanding common stock.

What type of security in Biogen Inc (BIIB) is covered by this Schedule 13G/A?

The Schedule 13G/A covers Biogen Inc common stock with CUSIP 09062X103. FMR LLC and Abigail P. Johnson report their beneficial ownership and associated voting and dispositive powers over this class of securities.

Where is FMR LLC’s principal office for its Biogen Inc (BIIB) holdings?

FMR LLC lists its principal business office as 245 Summer Street, Boston, Massachusetts 02210. Biogen Inc’s principal executive offices are at 225 Binney Street, Cambridge, MA 02142, as disclosed in the same Schedule 13G/A.

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

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Available on EDGAR 08/06/2026 - 10:18 AM Accepted by SEC EDGAR 08/06/2026 - 10:17 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 3)

BIOGEN INC

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

09062X103

(CUSIP Number)

06/30/2026

(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 16,623,432.57
6	Shared Voting Power 0.00
7	Sole Dispositive Power 18,294,523.51
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

18,294,523.51

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)

12.4 %

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 18,294,523.51
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

18,294,523.51

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)

12.4 %

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: 18294523.51
(b)	Percent of class: 12.4 %
(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: 18294523.51
	(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:	08/05/2026

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:	08/05/2026

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.