X0508 4 2026-02-20 0 0001619856 Caribou Biosciences, Inc. CRBU 0001670579 Haurwitz Rachel E. C/O CARIBOU BIOSCIENCES, INC. 2929 7TH STREET, SUITE 105 BERKELEY CA 94710 1 1 0 0 President and CEO 0 Common Stock 2026-02-20 4 A 0 151700 0 A 447150 D Common Stock 3369395 I By Trust Option to purchase Common Stock 1.80 2026-02-20 4 A 0 682500 0 A 2036-02-19 Common Stock 682500 682500 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. Shares are held by The City Canyon Family Trust dated May 31, 2021, of which the Reporting Person is a Co-Trustee with her spouse. 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. The reporting person has elected, consistent with the terms of a durable sell-to-cover instruction, to pay cash to satisfy withholding tax obligations due in connection with the February 20, 2026 vesting of previously-granted RSUs. /s/ Barbara G. McClung, as attorney-in-fact 2026-02-20