BIOGEN INC. — Director's Dealing 2015

Oct 5, 2015

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN INC. (BIIB)
CIK: 0000875045
Period of Report: 2015-10-01

Reporting Person: Karaboutis Adriana (EVP, Tech. and Bus. Solutions)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2015-10-01	Common Stock	M	1939	—	Acquired	10446	Direct
2015-10-01	Common Stock	F	804	$287.30	Disposed	9642	Direct
2015-10-01	Common Stock	F	862	$287.30	Disposed	8780	Direct
2015-10-02	Common Stock	S	417	$283.38	Disposed	8363	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2015-10-01	Restricted Stock Unit	$0	M	1939	Disposed	2017-10-01	Common Stock (1939)	Direct
2015-10-01	Restricted Stock Unit	$0	J	2323	Disposed	2017-10-01	Common Stock (2323)	Direct

Footnotes

F1: Sale pursuant to a trading plan intended to comply with Rule 10b5-1 of the Securities Exchange Act of 1934.

F2: 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 Idec 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]).

F3: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number of shares that vested.