Certain Common Stock of C4 Therapeutics, Inc. are subject to a Lock-Up Agreement Ending on 15-SEP-2021. These Common Stock will be under lockup for 91 days starting from 16-JUN-2021 to 15-SEP-2021. Details: The executive officers, directors have entered into lock-up agreements with the underwriters prior to the commencement of this offering pursuant to which each lock-up party, with limited exceptions, for a period of 90 days after the date of this prospectus may not without the prior written consent of J.P. Morgan Securities LLC, Jefferies LLC and Evercore Group L.L.C.: (i) sell or offer to sell any shares of common stock or Related Securities by such person or their family member, (ii) enter into any swap, (iii) make any demand for, or exercise any right with respect to, the registration under the Securities Act of the offer and sale of any shares of common stock or Related Securities, or cause to be filed a registration statement, prospectus or prospectus supplement (or an amendment or supplement thereto) with respect to any such registration, or (iv) publicly announce an intention to do any of the foregoing.