BIOGEN INC. — Director's Dealing 2026

Feb 10, 2026

SEC Form 4 — Statement of Changes in Beneficial Ownership

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

Reporting Person: ALEXANDER SUSAN H (EVP Chief Legal Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2026-02-06	Common Stock	M	2190	—	Acquired	38455	Direct
2026-02-06	Common Stock	F	1059	$201.18	Disposed	37396	Direct
2026-02-06	Common Stock	M	1940	—	Acquired	39336	Direct
2026-02-06	Common Stock	F	931	$201.18	Disposed	38405	Direct
2026-02-06	Common Stock	M	4916	—	Acquired	43321	Direct
2026-02-06	Common Stock	F	1514	$201.18	Disposed	41807	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2026-02-06	Restricted Stock Unit	$0	M	2190	Disposed	2026-02-08	Common Stock (2190)	Direct
2026-02-06	Restricted Stock Unit	$0	M	1940	Disposed	2027-02-07	Common Stock (1940)	Direct
2026-02-06	Restricted Stock Unit	$0	M	4916	Disposed	2028-02-06	Common Stock (4916)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	20082	Indirect

Footnotes

F1: The restricted stock units vest in three (3) equal annual installments commencing one year after the grant date of 2/8/2023.

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

F3: The restricted stock units vest in three equal yearly installments beginning on the first anniversary of the grant date of February 6, 2025.