X0306 4 2015-11-10 0 0000855654 IMMUNOGEN INC IMGN 0001508596 Peterson Kristine 8 OLD BARN COURT NEWTOWN PA 18940 1 0 0 0 Deferred Share Unit 0 2015-11-10 4 A 0 3000 0 A 2016-02-01 Common Stock 3000 15454 D Stock option (right to buy) 13.07 2015-11-10 4 A 0 10000 13.07 A 2016-02-01 2025-11-10 Common Stock 10000 10000 D The deferred share units were issued pursuant to the Issuer's Compensation Policy for Non-Employee Directors and are convertible into Common Stock on a one-to-one basis. The vested deferred share units are to be settled 100% in shares of Common Stock of the Company upon the reporting person's retirement from the Board of Directors. The deferred share units vest ratably over a one year period in quarterly increments beginning on February 1, 2016, contingent upon the individual remaining a director as of each vesting date. Exercisable as to 2,500 shares commencing on February 1, 2016, 2,500 shares commencing on May 1, 2016, 2,500 shares commencing on August 1, 2016 and 2,500 shares commencing on November 1, 2016, contingent upon the individual remaining a director as of each vesting date. /s/ Craig Barrows, attorney in fact 2015-11-12