BIOGEN INC. — Director's Dealing 2025

Dec 3, 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN INC. (BIIB)
CIK: 0000875045
Period of Report: 2025-12-01

Reporting Person: Viehbacher Christopher (Director, President and CEO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-12-01	Common Stock	M	7040	—	Acquired	19847	Direct
2025-12-01	Common Stock	F	3404	$177.78	Disposed	16443	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-12-01	Restricted Stock Unit	$	M	7040	Disposed		Common Stock (7040)	Direct

Footnotes

F1: Each Restricted Stock Unit ("RSU") represents the right to receive, at settlement, one share of common stock.

F2: Each RSU vested on the third anniversary of the grant date of December 1, 2022.