X0306 4 2022-06-15 0000875045 BIOGEN INC. BIIB 0001361754 DENNER ALEXANDER J BIOGEN INC. 225 BINNEY ST. CAMBRIDGE MA 02142 1 Common Stock 2022-06-15 4 A 0 1370 0 A 15099 D Common Stock 643000 I See Footnotes Dr. Denner disclaims beneficial ownership of the shares being reported on this Form 4 except to the extent of his pecuniary interest therein. Sarissa Capital Management LP ("Sarissa Capital") is the investment advisor to certain investment funds, including the funds that directly beneficially own the securities reported herein (the "Sarissa Funds"). Alexander Denner is the Chief Investment Officer of Sarissa Capital and controls the ultimate general partner of the Sarissa Funds. By virtue of the foregoing, Dr. Denner may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 of the Securities Exchange Act of 1934, as amended) the shares that the Sarissa Funds directly beneficially own. /s/ Wendell Taylor, Attorney in Fact for Alexander J. Denner 2022-06-17