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: Keeney Adam (Head of Corporate Development)

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-02-07	Common Stock	M	1801	—	Acquired	2463	Direct
2025-02-07	Common Stock	F	563	$141.35	Disposed	1900	Direct

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-02-06	Restricted Stock Unit	$0	A	9835	Acquired	2028-02-06	Common Stock (9835)	Direct
2025-02-07	Restricted Stock Unit	$0	M	1801	Disposed	2027-02-07	Common Stock (1801)	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.