C4 Therapeutics Inc

Trading Arrangements

The following table describes, for three months ended March 31, 2024, each trading arrangement for the purchase or sale of Company securities adopted, modified or terminated by our directors and officers that is either (1) a contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c), or a Rule 10b5-1 trading arrangement, or (2) a “non-Rule 10b5-1 trading arrangement” (as defined in Item 408(c) of Regulation S-K):

During the three months ended March 31, 2024, the Company's directors and officers (as defined in Rule 1a-1(f) under the Exchange Act) adopted plans intended to satisfy the affirmative defense conditions of Securities Exchange Act Rule 10b5-1(c) for the sale of the Company's securities as set forth below.

(1) Except as otherwise indicated, each trading arrangement permitted or permits transactions through and including the earlier to occur of (a) the completion of all purchases or sales, (b) the date listed in this column or (c) the date the trading arrangement is otherwise terminated.

(2) Ms. Adam's Rule 10b5-1 Trading Plan provides for the sale of up to (i) 169,557 shares of common stock and (ii) an indeterminable number of shares of common stock from the settlement of RSUs. The number of shares of common stock in clause (ii) is indeterminable because the number will vary based on the extent to which vesting conditions are satisfied, the market price of the Company's common stock at the time of settlement and the number of shares that would otherwise be issuable on each settlement date of a covered RSU that are sold or withheld in an amount sufficient to satisfy the applicable tax withholding obligations.

(3) Ms. Adam's prior Rule 10b5-1 Trading Plan provided for the sale of up to (i) 65,531 shares of common stock and (ii) an indeterminable number of shares of common stock from the settlement of RSUs or PSUs. The number of shares of common stock in clause (ii) is indeterminable because the number would have varied based on the extent to which vesting conditions were satisfied, the market price of the Company's common stock at the time of settlement and the number of shares that would otherwise be issuable on each settlement date of a covered RSU or PSU sold or withheld in an amount sufficient to satisfy the applicable tax withholding obligations.

(4) As of the date of termination, no shares had been sold under this Rule 10b5-1 trading arrangement.

(5) Mr. Boyle's Rule 10b5-1 Trading Plan provides for the sale of up to (i) 42,191 shares of common stock and (ii) an indeterminable number of shares of common stock from the settlement of RSUs. The number of shares of common stock in clause (ii) is indeterminable because the number will vary based on the extent to which vesting conditions are satisfied, the market price of the Company's common stock at the time of settlement and the number of shares that would otherwise be issuable on each settlement date of a covered RSU that are sold or withheld in an amount sufficient to satisfy the applicable tax withholding obligations.

(6) Ms. Schick's Rule 10b5-1 Trading Plan provides for the sale of up to (i) 37,846 shares of common stock and (ii) an indeterminable number of shares of common stock from the settlement of RSUs and PSUs. The number of shares of common stock in clause (ii) is indeterminable because the number will vary based on the extent to which vesting conditions are satisfied, the market price of the Company's common stock at the time of settlement and the number of shares that would otherwise be issuable on each settlement date of a covered RSU or PSU that are sold or withheld in an amount sufficient to satisfy the applicable tax withholding obligations.