BIOGEN INC. — Director's Dealing 2024

Feb 21, 2024

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN INC. (BIIB)
CIK: 0000875045
Period of Report: 2024-02-16

Reporting Person: Kramer Robin (Chief Accounting Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2024-02-16	Common Stock	M	914	—	Acquired	6191.7483	Direct
2024-02-16	Common Stock	F	269	$219.08	Disposed	5922.7483	Direct
2024-02-16	Common Stock	M	431	—	Acquired	6353.7483	Direct
2024-02-16	Common Stock	F	127	$219.08	Disposed	6226.7483	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2024-02-16	Performance Stock Unit	$0	M	914	Disposed	2024-02-18	Common Stock (914)	Direct
2024-02-16	Restricted Stock Unit	$0	M	431	Disposed	2024-02-18	Common Stock (431)	Direct
2024-02-16	Restricted Stock Unit	$0	J	537	Disposed	2024-02-18	Common Stock (537)	Direct

Footnotes

F1: This award was granted to the reporting person on February 18, 2021. The number of RSUs reported represented the maximum possible number of shares that were eligible for vesting, which is 200% of the number of shares at target
payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common
stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing
stock price following and including the grant date]).

F2: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.