X0306 4 2017-05-01 0000875045 BIOGEN INC. BIIB 0001672709 Vounatsos Michel BIOGEN INC. 225 BINNEY ST. CAMBRIDGE MA 02142 1 1 Chief Executive Officer Common Stock 2017-05-01 4 P 0 1402 271.35 A 2927.458 D Purchase pursuant to a trading plan intended to comply with Rule 10b5-1 of the Securities Exchange Act of 1934. Includes 91.527 shares acquired under the Biogen Inc. employee stock purchase plan on 3/31/2017. Suzanne Murray, Attorney in Fact for Michel Vounatsos 2017-05-02