X0306 4/A 2019-09-18 2019-09-20 0 0001496323 IGM Biosciences, Inc. IGMS 0001785882 Topsoe Jakob Haldor C/O IGM BIOSCIENCES, INC. 325 E. MIDDLEFIELD ROAD MOUNTAIN VIEW CA 94043 1 0 1 0 Common Stock 2019-09-18 4 P 0 1700 19.5365 A 36075 D Common Stock 10289453 I See footnote The shares and the purchase price reflected herein are amended to correct scrivenor's errors in the previously filed Form 4. All shares are held directly by Haldor Topsoe Holding A/S (HTH). Mr. Jakob Haldor Topsoe, Ms. Christina Teng Topsoe, Mr. Martin Topsoe and Mr. Emil Oigaard, members of the board of directors of HTH, may be deemed to share voting and investment power with respect to the shares reported herein and disclaim beneficial ownership of such shares, except to the extent of his or her pecuniary interest therein, if any. Mr. Jakob Haldor Topsoe and Ms. Christina Teng Topsoe are members of the Issuer's board of directors. /s/ Misbah Tahir, by power of attorney 2019-09-23