X0306 4 2020-12-11 0 0001662579 C4 Therapeutics, Inc. CCCC 0001824863 Fisher Stewart C/O C4 THERAPEUTICS, INC. 490 ARSENAL WAY #200 WATERTOWN MA 02472 0 1 0 0 Chief Scientific Officer Common Stock 2020-12-11 4 M 0 4743 2.11 A 90115 D Common Stock 2020-12-11 4 M 0 9701 3.71 A 99816 D Common Stock 2021-02-03 4 M 0 2371 2.11 A 102187 D Common Stock 2021-02-03 4 M 0 5929 3.71 A 108116 D Stock Option (Right to Buy) 2.11 2020-12-11 4 M 0 4743 0.00 D 2026-07-12 Common Stock 4743 4742 D Stock Option (Right to Buy) 3.71 2020-12-11 4 M 0 9701 0.00 D 2028-04-23 Common Stock 9701 61443 D Stock Option (Right to Buy) 2.11 2021-02-03 4 M 0 2371 0.00 D 2026-07-12 Common Stock 2371 2371 D Stock Option (Right to Buy) 3.71 2021-02-03 4 M 0 5929 0.00 D 2028-04-23 Common Stock 5929 55514 D The Form 3 filed on October 1, 2020 included an incorrect exercise price in Table II, Column 2 ($3.72). Represents underlying unexercised stock options that were granted on July 13, 2016. The terms of the original grant provide that 20% of this option vested and became exercisable on May 2, 2017, with the remainder vesting in 16 equal quarterly installments thereafter. Represents underlying unexercised stock options that were granted on April 24, 2018. The terms of the original grant provide that 20% of this option vested and became exercisable on May 1, 2019, with the remainder vesting in 16 equal quarterly installments thereafter. /s/ Jolie M. Siegel, Attorney-in-Fact 2021-02-04