X0508 4 2026-02-20 0 0001619856 Caribou Biosciences, Inc. CRBU 0001754067 Kelly Timothy P C/O CARIBOU BIOSCIENCES, INC. 2929 7TH STREET, SUITE 105 BERKELEY CA 94710 0 1 0 0 Chief Technology Officer 0 Common Stock 2026-02-20 4 A 0 45000 0 A 82500 D Common Stock 2026-02-24 4 S 0 3147 1.96 D 79353 D Option to purchase Common Stock 1.80 2026-02-20 4 A 0 202500 0 A 2036-02-19 Common Stock 202500 202500 D This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date. Reflects the number of shares of common stock that were sold pursuant to the Issuer's mandatory sell-to-cover policy for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person. 1/48 of the total number of shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2030, subject to the reporting person continuing to provide service to the Issuer through each such vesting date. /s/ Barbara G. McClung, as attorney-in-fact 2026-02-24