X0306 4 2022-01-26 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 Common Stock 2022-01-26 4 M 0 10000 2.96 A 3359395 D Option to purchase Common Stock 2.96 2022-01-26 4 M 0 10000 0.00 D 2023-06-11 Common Stock 10000 126350 D Due to a rounding error, the exercise price for this stock option was inadvertently originally reported as $2.95 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 12, 2019 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 until the option is fully vested on June 12, 2022, subject to the reporting person's continued services to the Issuer through the applicable vesting dates. /s/ Barbara G. McClung, as attorney-in-fact 2022-01-27