Rachel E. Haurwitz - Mar 20, 2023 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: Mar 20, 2023
Transactions value $: $29,600
Form type: 4
Date filed: 3/22/2023, 04:16 PM
Previous filing: Feb 23, 2023
Next filing: Jun 9, 2023

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	CRBU	Common Stock	Options Exercise	$29.6K	+10K	+50%	$2.96	30K	Mar 20, 2023	Direct
holding	CRBU	Common Stock						3.35M	Mar 20, 2023	by Trust	F1

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	-8.59%	$0.00	106K	Mar 20, 2023	Common Stock	10K	$2.96	Direct	F2

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

Explanation of Responses:

Id	Content
F1	Shares are held by The City Canyon Trust Dated May 31, 2021, of which the reporting person is a Co-Trustee with her spouse.
F2	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 vested on the corresponding day of each month thereafter until the option became fully vested on June 12, 2022.