[Form 4] Biogen Inc. Insider Trading Activity

Rhea-AI Filing Summary

Priya Singhal, Head of Development at Biogen Inc. (BIIB), reported a series of equity transactions dated 08/29/2025 and 09/02/2025. A grant of 1,669 restricted stock units (RSUs) vested (recorded as an acquisition at $0) increasing her beneficial ownership before sales to 7,096.1428 shares. On 08/29/2025 she sold 807 shares at $132.22 and on 09/02/2025 she sold 517 shares at $133.55, leaving her with 5,772.1428 shares following the reported transactions. The filing notes the RSU award was granted on September 1, 2022 and vests in three equal annual installments.

Positive

• 10b5-1 plan indicated, suggesting the sales were pre-planned and compliant with insider trading rules
• RSU vesting documented, aligning executive compensation with long‑term incentives

Negative

• Net reduction in beneficial ownership from 7,096.1428 to 5,772.1428 shares after the reported transactions
• Total shares sold of 1,324 (807 at $132.22 and 517 at $133.55) reduced the officer's stake

Insights

Financial Analyst

TL;DR Insider sold shares after an RSU vesting; transactions appear routine and executed under a plan.

The reporting shows a net decrease in beneficial ownership from 7,096.1428 to 5,772.1428 shares following the vesting of 1,669 RSUs and subsequent sales of 807 and 517 shares at $132.22 and $133.55 respectively. The filer checked the box indicating the sale was made pursuant to a 10b5-1 plan, which signals pre‑planned disposition rather than opportunistic trading. For investors, these are administrative insider transactions tied to compensation vesting and liquidity rather than a clear signal about near‑term company fundamentals.

Corporate Governance Expert

TL;DR Transactions reflect standard executive compensation vesting and planned sales; governance controls (10b5-1) are documented.

The Form 4 documents the vesting of restricted stock units granted on September 1, 2022 that vest in three equal installments and subsequent share dispositions. The explicit 10b5-1 indication supports procedural compliance and reduces concerns about insider timing. The remaining holding of 5,772.1428 shares continues executive exposure to shareholder outcomes, while the sales provide the officer with realized liquidity from vested awards. No extraordinary governance issues or unusual concentrations are disclosed in this filing.

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

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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

X

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^*

Singhal Priya

(Last) (First) (Middle)

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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Head of Development

3. Date of Earliest Transaction (Month/Day/Year)
08/29/2025

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	08/29/2025		M		1,669	A	$0	7,096.1428	D
Common Stock	08/29/2025		F		807	D	$132.22	6,289.1428	D
Common Stock	09/02/2025		S		517	D	$133.55	5,772.1428	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	$0	08/29/2025		M			1,669	(1)	09/01/2025	Common Stock	1,669	$0	0	D

Explanation of Responses:

1. This award was granted to the reporting person on September 1, 2022 and will vest in three equal installments on each anniversary of the grant date.

	/s/ Wendell Taylor, attorney-in-fact for Priya Singhal	09/02/2025
	** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What transactions did Priya Singhal report on the Form 4 for BIIB?

The filing reports the vesting acquisition of 1,669 RSUs (recorded at $0) and sales of 807 shares at $132.22 and 517 shares at $133.55.

How many shares does Priya Singhal beneficially own after the reported transactions?

Following the reported transactions Priya Singhal beneficially owns 5,772.1428 shares.

Were the sales executed under a trading plan (10b5-1)?

Yes. The filer checked the box indicating the transaction was made pursuant to a 10b5-1 plan.

When were the underlying RSUs originally granted and what is the vesting structure?

The RSU award was granted on September 1, 2022 and vests in three equal annual installments.

What prices were the shares sold for in the reported transactions?

The sales prices were $132.22 for 807 shares and $133.55 for 517 shares.