BIOGEN INC. — Director's Dealing 2017

Mar 3, 2017

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN INC. (BIIB)
CIK: 0000875045
Period of Report: 2017-03-01

Reporting Person: McKenzie Paul (EVP Pharmaceutical Oper & Tech)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-03-01	Common Stock	M	481	—	Acquired	718.443	Direct
2017-03-01	Common Stock	F	157	$293.26	Disposed	561.443	Direct
2017-03-01	Common Stock	A	2730	—	Acquired	3291.443	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2017-03-01	Restricted Stock Unit	$0	M	481	Disposed	2019-03-01	Common Stock (481)	Direct
2017-03-01	Restricted Stock Unit	$0	J	363	Disposed	2019-03-01	Common Stock (363)	Direct

Footnotes

F1: Includes 27.114 shares acquired under the Biogen Inc. employee stock purchase plan on 9/30/2016 and 12/30/2016.

F2: This award was previously reported as covering 2,480 shares, but was adjusted pursuant to the anti-dilution provisions of the award in connection with the spin-off of Bioverativ, Inc. on February 1, 2017

F3: The number of RSUs reported represents the maximum possible number of shares that are 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 on the grant date]).

F4: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.