BIOGEN INC. - Director's Dealing 2026

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN INC. (BIIB)
CIK: 0000875045
Period of Report: 2026-02-06

Reporting Person: Gregory Ginger (EVP, Human Resources)

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2026-02-06	Common Stock	M	1635	—	Acquired	19399.7673	Direct
2026-02-06	Common Stock	F	791	$201.18	Disposed	18608.7673	Direct
2026-02-06	Common Stock	M	1802	—	Acquired	20410.7673	Direct
2026-02-06	Common Stock	F	666	$201.18	Disposed	19744.7673	Direct
2026-02-06	Common Stock	M	3746	—	Acquired	23490.7673	Direct
2026-02-06	Common Stock	F	1132	$201.18	Disposed	22358.7673	Direct

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2026-02-06	Restricted Stock Unit	$0	M	1635	Disposed	2026-02-08	Common Stock (1635)	Direct
2026-02-06	Restricted Stock Unit	$0	M	1802	Disposed	2027-02-07	Common Stock (1802)	Direct
2026-02-06	Restricted Stock Unit	$0	M	3746	Disposed	2028-02-06	Common Stock (3746)	Direct

F1: Includes 166.6667 shares acquired under the Biogen Inc. employee stock purchase plan on 3/31/2025.

F2: The restricted stock units vest in three (3) equal annual installments commencing one year after the grant date of 02/08/2023.

F3: The restricted stock units vest in three (3) equal annual installments, commencing one year after the grant date of 02/07/2024.

F4: The restricted stock units vest in three equal yearly installments beginning on the first anniversary of the grant date of February 6, 2025.