Rachel E. Haurwitz - May 9, 2022 Form 4 Insider Report for Caribou Biosciences, Inc. (CRBU)

Role: President and CEO, Director
Signature: /s/ Barbara G. McClung, as attorney-in-fact
Stock symbol: CRBU
Transactions as of: May 9, 2022
Transactions value $: $29,600
Form type: 4
Date filed: 5/10/2022, 07:32 PM
Previous filing: May 10, 2022
Next filing: Jun 17, 2022

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	CRBU	Common Stock	Options Exercise	$29.6K	+10K	+100%	$2.96	20K	May 9, 2022	Direct	F1
holding	CRBU	Common Stock						3.35M	May 9, 2022	By Trust	F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	CRBU	Option to purchase Common Stock	Options Exercise	$0	-10K	-7.91%	$0.00	116K	May 9, 2022	Common Stock	10K	$2.96	Direct	F1, F3

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	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.
F2	Shares are held by The City Canyon Trust Dated May 31, 2021, of which the reporting person is a Co-Trustee with her spouse.
F3	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 this 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 service to the Issuer through the applicable vesting dates.