BIOGEN INC. - Director's Dealing 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN INC. (BIIB)
CIK: 0000875045
Period of Report: 2025-02-06

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

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-02-07	Common Stock	M	9008	—	Acquired	16008	Direct
2025-02-07	Common Stock	F	3201	$141.35	Disposed	12807	Direct

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-02-06	Restricted Stock Unit	$0	A	46360	Acquired	2028-02-06	Common Stock (46360)	Direct
2025-02-07	Restricted Stock Unit	$0	M	9008	Disposed	2027-02-07	Common Stock (9008)	Direct

F1: The restricted stock units vest in three equal yearly installments beginning on the first anniversary of the grant date of February 6, 2025.

F2: The restricted stock units vest in three (3) equal annual installments, commencing one year after the grant date of 02/07/2024.