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: Karaboutis Adriana (EVP, Tech, Bus. Sol & Corp Aff)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-02-28	Common Stock	M	570	—	Acquired	7996	Direct
2017-02-28	Common Stock	F	253	$284.75	Disposed	7743	Direct
2017-02-28	Common Stock	M	1494	—	Acquired	9237	Direct
2017-02-28	Common Stock	F	485	$287.63	Disposed	8752	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
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	952	Disposed	2018-02-23	Common Stock (952)	Direct
2017-02-28	Restricted Stock Unit	$0	M	570	Disposed	2018-02-23	Common Stock (570)	Direct
2017-02-28	Restricted Stock Unit	$0	M	1494	Disposed	2019-02-22	Common Stock (1494)	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 represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number of shares that vested.

F4: 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]).

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: This award was previously reported as covering 2,974 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.

F7: 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.