Steven Kanner - Oct 12, 2021 Form 4 Insider Report for Caribou Biosciences, Inc. (CRBU)

Role: Chief Scientific Officer
Signature: /s/ Barbara G. McClung, as attorney-in-fact
Stock symbol: CRBU
Transactions as of: Oct 12, 2021
Transactions value $: $220,757
Form type: 4
Date filed: 10/13/2021, 07:31 PM
Previous filing: Jul 22, 2021
Next filing: Dec 21, 2021

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	CRBU	Common Stock	Purchase	$180K	+99.5K	+99.38%	$1.81	200K	Oct 12, 2021	Direct	F1
transaction	CRBU	Common Stock	Purchase	$1.26K	+698	+0.35%	$1.81	200K	Oct 12, 2021	Direct	F1
transaction	CRBU	Common Stock	Purchase	$39.3K	+14.6K	+7.29%	$2.69	215K	Oct 12, 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	-99.5K	-58.08%	$0.00	71.8K	Oct 12, 2021	Common Stock	99.5K	$1.81	Direct	F3
transaction	CRBU	Option to purchase Common Stock	Exercise of in-the-money or at-the-money derivative security	$0	-698	-12.52%	$0.00	4.88K	Oct 12, 2021	Common Stock	698	$1.81	Direct	F3
transaction	CRBU	Option to purchase Common Stock	Exercise of in-the-money or at-the-money derivative security	$0	-14.6K	-9.96%	$0.00	132K	Oct 12, 2021	Common Stock	14.6K	$2.69	Direct	F2, 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 22, 2021.
F3	This option became fully exercisable on June 30, 2021.
F4	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.