Caribou director granted 45,000 stock options

Sacks Natalie reported acquisition or exercise transactions in this Form 4 filing.

Rhea-AI Filing Summary

Sacks Natalie reported acquisition or exercise transactions in this Form 4 filing.

Caribou Biosciences, Inc. reported that director Natalie Sacks received an option grant to purchase 45,000 shares of common stock. The option was awarded at a price of $0.00 per share, reflecting a no-cost equity award rather than an open-market purchase.

According to the vesting terms, one-twelfth of the option shares will vest on each monthly anniversary of the grant date, so the award will be fully vested by February 20, 2027, assuming she continues providing service to the company through each vesting date.

Insider Trade Summary

Grant/Award: 45,000 shares

Grant/Award 1 txn

Insider Sacks Natalie

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Option to purchase Common Stock	45,000	$0.00	$0.00

Holdings After Transaction: Option to purchase Common Stock — 45,000 contracts (Direct)

Footnotes (1)

1. F1. 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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Caribou Biosciences (CRBU) report for Natalie Sacks?

Caribou Biosciences reported that director Natalie Sacks received an option grant for 45,000 shares of common stock. The option was awarded at an exercise price of $0.00 per share, indicating a no-cost equity award rather than a market transaction.

How many Caribou Biosciences (CRBU) shares are covered by Natalie Sacks’ new option?

The new stock option awarded to director Natalie Sacks covers 45,000 shares of Caribou Biosciences common stock. All 45,000 shares are reflected as beneficially owned following the transaction, subject to the specified vesting schedule tied to her continued service to the company.

What is the vesting schedule for Natalie Sacks’ Caribou Biosciences (CRBU) stock option?

The option vests in equal monthly installments, with one-twelfth of the 45,000 shares vesting on each monthly anniversary of the grant date. The award will be fully vested on February 20, 2027, provided she continues to provide service through each vesting date.

At what exercise price was Natalie Sacks’ Caribou Biosciences (CRBU) option granted?

The option to purchase Caribou Biosciences common stock granted to director Natalie Sacks carries an exercise price of $0.00 per share. This indicates the award is a no-cost equity grant rather than a purchase of shares in the open market.

Is Natalie Sacks’ Caribou Biosciences (CRBU) option grant a direct or indirect holding?

The Form 4 indicates that Natalie Sacks’ option to purchase 45,000 Caribou Biosciences shares is held as a direct ownership position. The transaction is reported as a grant or award acquisition rather than a purchase or sale of existing shares.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 02/20/2026 - 05:28 PM EST Learn about SEC filing dates

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

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

Sacks Natalie

(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.