Ryan Fischesser - Dec 20, 2021 Form 4 Insider Report for Caribou Biosciences, Inc. (CRBU)

Role: VP of Finance and Controller
Signature: /s/ Barbara G. McClung as, attorney-in-fact
Stock symbol: CRBU
Transactions as of: Dec 20, 2021
Transactions value $: $3,056
Form type: 4
Date filed: 12/21/2021, 04:23 PM
Previous filing: Oct 12, 2021
Next filing: Jan 12, 2022

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	CRBU	Common Stock	Purchase	$3.06K	+1.14K	+1.13%	$2.69	102K	Dec 20, 2021	Direct	F1, 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	Exercise of in-the-money or at-the-money derivative security	$0	-1.14K	-13.33%	$0.00	7.38K	Dec 20, 2021	Common Stock	1.14K	$2.69	Direct	F2, F3
transaction	CRBU	Option to purchase Common Stock	Award	$0	+40K		$0.00	40K	Dec 20, 2021	Common Stock	40K	$15.16	Direct	F4

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

Explanation of Responses:

Id	Content
F1	These shares were acquired pursuant to the exercise of a stock option, as reported in Table II below.
F2	The exercise price for this stock option was incorrectly reported as $2.68 per share on the reporting person's Form 3 filed on July 23, 2021.
F3	The shares subject to this option have vested or will vest in equal monthly installments until the option is fully vested on January 1, 2023, subject to the reporting person's continued service to the Issuer through the applicable vesting dates.
F4	The shares subject to this option will vest in equal monthly installments starting on the first monthly anniversary of the grant date until the option is fully vested on December 20, 2025, subject to the reporting person's continued service to the Issuer through the applicable vesting dates.