BIOGEN INC. — Director's Dealing 2017

Mar 2, 2017

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN INC. (BIIB)
CIK: 0000875045
Period of Report: 2017-02-28

Reporting Person: DiPietro Kenneth (EVP Human Resources)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-02-28	Common Stock	M	728	—	Acquired	4665	Direct
2017-02-28	Common Stock	F	335	$284.75	Disposed	4330	Direct
2017-02-28	Common Stock	M	1494	—	Acquired	5824	Direct
2017-02-28	Common Stock	F	485	$287.63	Disposed	5339	Direct
2017-02-28	Common Stock	M	1174	—	Acquired	6513	Direct
2017-02-28	Common Stock	F	553	$274.76	Disposed	5960	Direct
2017-02-28	Common Stock	M	2300	—	Acquired	8260	Direct
2017-02-28	Common Stock	F	1083	$274.76	Disposed	7177	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2017-02-28	Restricted Stock Unit	$0	J	1378	Disposed	2017-02-12	Common Stock (1378)	Direct
2017-02-28	Restricted Stock Unit	$0	J	1198	Disposed	2019-02-22	Common Stock (1198)	Direct
2017-02-28	Restricted Stock Unit	$0	J	1216	Disposed	2018-02-23	Common Stock (1216)	Direct
2017-02-28	Restricted Stock Unit	$0	M	728	Disposed	2018-02-23	Common Stock (728)	Direct
2017-02-28	Restricted Stock Unit	$0	M	1494	Disposed	2019-02-22	Common Stock (1494)	Direct
2017-02-28	Restricted Stock Unit	$0	M	1174	Disposed	2017-02-12	Common Stock (1174)	Direct
2017-02-28	Restricted Stock Unit	$0	M	2300	Disposed	2017-02-12	Common Stock (2300)	Direct
2017-02-28	Restricted Stock Unit	$0	J	1	Disposed	2017-02-12	Common Stock (1)	Direct

Footnotes

F1: This award vested on 2/23/2017 and the actual number of shares that vested was determined in accordance with the terms of such award. Due to adjustments to the award to account for the Bioverativ Inc. spin-off, the number of vested shares was not determinable until 2/28/2017. Such adjusted number of vested shares was distributed to the reporting person on 2/28/2017.

F2: This award vested on 2/22/2017 and the actual number of shares that vested was determined in accordance with the terms of such award. Due to adjustments to the award to account for the Bioverativ Inc. spin-off, the number of vested shares was not determinable until 2/28/2017. Such adjusted number of vested shares was distributed to the reporting person on 2/28/2017.

F3: This award vested on 2/12/2017 and the actual number of shares that vested was determined in accordance with the terms of such award. Due to adjustments to the award to account for the Bioverativ Inc. spin-off, the number of vested shares was not determinable until 2/28/2017. Such adjusted number of vested shares was distributed to the reporting person on 2/28/2017.

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

F5: 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]).

F6: 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]).

F7: This award was previously reported as covering 3,802 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

F8: This award was previously reported as covering 7,900 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

F9: This award was previously reported as covering 2,494 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

F10: This award was previously reported as covering 2,249 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

F11: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 150% of the number of shares at target payout. One-fourth of these RSUs are eligible to vest on each of the first four 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 average 60 calendar-day closing stock price ending on the vesting date divided by the average 60 calendar-day closing stock price on the grant date]).