X0508 4 2026-02-20 0 0001619856 Caribou Biosciences, Inc. CRBU 0001917391 Albertson Tina M. C/O CARIBOU BIOSCIENCES, INC. 2929 7TH STREET, SUITE 105 BERKELEY CA 94710 0 1 0 0 Chief Medical Officer 1 Common Stock 2026-02-20 4 A 0 55000 0 A 69589 D Common Stock 2026-02-24 4 S 0 1066 1.96 D 68523 D Option to purchase Common Stock 1.80 2026-02-20 4 A 0 247500 0 A 2036-02-19 Common Stock 247500 247500 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 in a "sell-to-cover" transaction 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. This transaction was made pursuant to a Rule 10b5-1 trading plan in the form of a durable sell-to-cover instruction adopted by the reporting person on August 12, 2024. The trading plan provides for the automatic sale of shares of common stock necessary to satisfy the reporting person's tax withholding obligations incurred in connection with the vesting of RSUs. 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