Biogen (BIIB) CEO Viehbacher reports 7,040 RSU shares and 3,404 share sale

Rhea-AI Filing Summary

Biogen Inc. President and CEO Christopher A. Viehbacher reported equity transactions in the company’s common stock. On December 1, 2025, 7,040 shares of common stock were acquired at a price of $0 per share through the exercise of previously granted restricted stock units, coded as transaction type M. On the same date, 3,404 shares of common stock were disposed of in a transaction coded F at a price of $177.78 per share. After these transactions, Viehbacher beneficially owned 16,443 shares of Biogen common stock directly. The underlying restricted stock unit award, originally granted on December 1, 2022, vested on its third anniversary and represented one share of common stock for each unit.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Viehbacher Christopher

(Last) (First) (Middle)

BIOGEN INC.

225 BINNEY

(Street)

CAMBRIDGE MA 02142

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
BIOGEN INC. [ BIIB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	President and CEO

3. Date of Earliest Transaction (Month/Day/Year)
12/01/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	12/01/2025		M		7,040	A	$0	19,847	D
Common Stock	12/01/2025		F		3,404	D	$177.78	16,443	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Unit	(1)	12/01/2025		M			7,040	(2)	(2)	Common Stock	7,040	$0	0	D

Explanation of Responses:

1. Each Restricted Stock Unit ("RSU") represents the right to receive, at settlement, one share of common stock.

2. Each RSU vested on the third anniversary of the grant date of December 1, 2022.

	/s/ Wendell Taylor, attorney-in-fact for Christopher A. Viehbacher	12/03/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

What insider transaction did Biogen (BIIB) report for its CEO?

Biogen reported that President and CEO Christopher A. Viehbacher acquired 7,040 shares of common stock on December 1, 2025 through the exercise of restricted stock units and disposed of 3,404 shares on the same date.

How many Biogen (BIIB) shares does the CEO own after the reported Form 4 transactions?

Following the reported transactions, Christopher A. Viehbacher beneficially owned 16,443 shares of Biogen common stock, held directly.

At what prices were the Biogen (BIIB) Form 4 transactions reported?

The 7,040 shares acquired via restricted stock units were reported at a price of $0 per share, while the 3,404 shares disposed of were reported at $177.78 per share.

What do the transaction codes M and F mean in the Biogen (BIIB) Form 4?

Code M relates to the acquisition of 7,040 shares upon exercise or settlement of a derivative security (restricted stock units). Code F reports the disposition of 3,404 shares of common stock.

What were the terms of the Biogen (BIIB) restricted stock units in this filing?

The filing explains that each restricted stock unit (RSU) represents the right to receive one share of Biogen common stock at settlement. The RSUs in this report vested on the third anniversary of the grant date of December 1, 2022.

Did the Biogen (BIIB) CEO retain any restricted stock units after this transaction?

After settlement of the 7,040 restricted stock units into common stock, the number of derivative securities reported as beneficially owned was 0, indicating no RSUs remaining from this award.