Caribou Biosciences (CRBU) director receives 45,000-share stock option grant

Rhea-AI Filing Summary

Caribou Biosciences director Zheng Ran received an option grant for 45,000 shares of common stock. The option was awarded at an exercise price of $0.00 per share, reflecting a compensatory equity award rather than a market purchase.

According to the vesting terms, one-twelfth of the option shares vest on each monthly anniversary of the February 20, 2026 grant date, so the award will be fully vested by February 20, 2027, as long as Zheng Ran continues providing services to Caribou Biosciences through each vesting date.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Zheng Ran

(Last) (First) (Middle)

C/O CARIBOU BIOSCIENCES, INC.

2929 7TH STREET, SUITE 105

(Street)

BERKELEY CA 94710

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Caribou Biosciences, Inc. [ CRBU ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
02/20/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Option to purchase Common Stock	$1.8	02/20/2026		A		45,000		(1)	02/19/2036	Common Stock	45,000	$0	45,000	D

Explanation of Responses:

1. One-twelfth of the 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, 2027, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

Remarks:

	/s/ Barbara G. McClung, as attorney-in-fact	02/20/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did Caribou Biosciences (CRBU) disclose for Zheng Ran?

Caribou Biosciences reported that director Zheng Ran received an option grant for 45,000 shares of common stock. This equity award was recorded at an exercise price of $0.00 per share, indicating a compensatory grant rather than an open-market stock purchase.

How many Caribou Biosciences (CRBU) shares are covered by Zheng Ran’s new option?

The new option granted to Zheng Ran covers 45,000 shares of Caribou Biosciences common stock. All 45,000 shares are reported as beneficially owned following the transaction, subject to the award’s vesting schedule and continued service conditions described in the filing footnote.

What is the exercise price of Zheng Ran’s Caribou Biosciences (CRBU) stock option?

The option granted to Zheng Ran has an exercise price of $0.00 per share. This zero exercise price confirms the award is a compensatory equity grant, not a typical market-based option that requires paying a cash exercise price to acquire the underlying shares.

How does Zheng Ran’s Caribou Biosciences (CRBU) option vest over time?

The option vests in monthly installments, with one-twelfth of the 45,000 shares vesting on each monthly anniversary of the grant date. It will be fully vested by February 20, 2027, provided Zheng Ran continues to provide services to the company throughout this period.

What service requirement is attached to Zheng Ran’s CRBU option grant?

Vesting of the option depends on continued service to Caribou Biosciences. Each monthly vesting installment, and full vesting by February 20, 2027, is conditioned on Zheng Ran continuing to provide service to the issuer through each applicable vesting date as specified.