X0306 4 2022-05-13 0 0001619856 Caribou Biosciences, Inc. CRBU 0001871131 Kanner Steven C/O CARIBOU BIOSCIENCES, INC. 2929 7TH STREET, SUITE 105 BERKELEY CA 94710 0 1 0 0 Chief Scientific Officer Common Stock 2022-05-13 4 M 0 68306 1.81 A 295945 D Common Stock 2022-05-13 4 M 0 6114 2.69 A 302059 D Option to purchase Common Stock 1.81 2022-05-13 4 M 0 68306 0.00 D 2027-07-11 Common Stock 68306 3534 D Option to purchase Common Stock 2.69 2022-05-13 4 M 0 6114 0.00 D 2029-09-30 Common Stock 6114 116849 D Due to a rounding error, the exercise price for this stock option was inadvertently originally reported as $2.68 per share on the reporting person's Form 3 filed on July 22, 2021. 1/4th of the shares subject to this option vested on June 30, 2018 and an additional 1/48th of the aggregate number of shares subject to the option vested on the corresponding day of each month thereafter (or the last day of the month, if there was no corresponding day of the month), subject to the reporting person's continued services to the Issuer through the applicable vesting dates. 1/4th of the shares subject to this option vested on October 1, 2020 and an additional 1/48th of the aggregate number of shares subject to the option have vested or will vest on the corresponding day of each month thereafter, subject to the reporting person's continued services to the Issuer through the applicable vesting dates. /s/ Barbara G. McClung, as attorney-in-fact 2022-05-17