Barbara G. McClung - 20 Feb 2026 Form 4 Insider Report for Caribou Biosciences, Inc. (CRBU)

Role: Chief Legal Officer
Signature: /s/ Barbara G. McClung
Issuer symbol: CRBU
Transactions as of: 20 Feb 2026
Net transactions value: -$13,598
Form type: 4
Filing time: 24 Feb 2026, 20:54:36 UTC
Previous filing: 21 Feb 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
MCCLUNG BARBARA G	Chief Legal Officer	C/O CARIBOU BIOSCIENCES, INC., 2929 7TH STREET, SUITE 105, BERKELEY	/s/ Barbara G. McClung	24 Feb 2026	0001231321

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	CRBU	Common Stock	Award	$0	+45,000	+10%	$0.000000	488,502	20 Feb 2026	Direct	F1
transaction	CRBU	Common Stock	Sale	$13,598	-6,938	-1.4%	$1.96	481,564	24 Feb 2026	Direct	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	Award	$0	+202,500		$0.000000	202,500	20 Feb 2026	Common Stock	202,500	$1.80	Direct	F3

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

Explanation of Responses:

Id	Content
F1	This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.
F2	Reflects the number of shares of common stock that were sold in a "sell-to-cover" transaction for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person. This transaction was made pursuant to a Rule 10b5-1 trading plan in the form of a durable sell-to-cover instruction adopted prior to the 2023 amendments to Rule 10b5-1. The trading plan provides for the automatic sale of shares of common stock necessary to satisfy the reporting person's tax withholding obligations incurred in connection with the vesting of RSUs.
F3	1/48 of the total number of shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2030, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.