Cullinan Therapeutics (CGEM) CSO exercises options and sells 11,742 shares

Rhea-AI Filing Summary

Cullinan Therapeutics, Inc. Chief Scientific Officer Jennifer Michaelson reported multiple equity transactions in company stock. On February 20, 2026, she exercised stock options for 8,000 shares of common stock at a stated exercise price of $4.30 per share, reflected through derivative and non-derivative entries. She then sold a total of 11,742 shares of common stock in open-market transactions at prices of $13.62 and $14.30 per share. A footnote states that a portion of the sales was made to cover personal income tax obligations upon vesting of restricted stock units and that the transactions were effected under a Rule 10b5-1 trading plan established on August 7, 2025. Following these transactions, her reported direct ownership remained in the range of approximately 180,000–190,000 shares of Cullinan Therapeutics common stock.

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).

X

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^*

Michaelson Jennifer

(Last) (First) (Middle)

C/O CULLINAN THERAPEUTICS, INC.

ONE MAIN STREET, SUITE 1350

(Street)

CAMBRIDGE MA 02142

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Cullinan Therapeutics, Inc. [ CGEM ]

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

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

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
Common Stock	02/20/2026		S(1)		3,742	D	$13.62	181,977	D
Common Stock	02/20/2026		M		8,000	A	$4.3	189,977	D
Common Stock	02/20/2026		S(2)		8,000	D	$14.3	181,977	D

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
Stock Option (Right to Buy)	$4.3	02/20/2026		M			8,000	(3)	10/28/2030	Common Stock	8,000	$0.00	124,987	D

Explanation of Responses:

1. Sale of shares to cover personal income tax obligations upon vesting of restricted stock units.

2. Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 on August 7, 2025.

3. 25% of the shares vested on July 4, 2020, and the remaining shares vested in 36 equal monthly installments thereafter.

	/s/ Jacquelyn Sumer, Attorney-in-Fact	02/23/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What insider transactions did Cullinan Therapeutics (CGEM) report for Jennifer Michaelson?

Cullinan Therapeutics reported that Chief Scientific Officer Jennifer Michaelson exercised options for 8,000 shares and sold 11,742 common shares. The transactions occurred on February 20, 2026 and were reported as open-market sales and derivative exercises in company stock.

How many Cullinan Therapeutics (CGEM) shares did Jennifer Michaelson sell and at what prices?

Jennifer Michaelson sold a total of 11,742 Cullinan Therapeutics common shares. The reported open-market sale prices were $13.62 per share for 3,742 shares and $14.30 per share for 8,000 shares, according to the insider transaction disclosure.

How many Cullinan Therapeutics (CGEM) shares did Jennifer Michaelson acquire through option exercises?

Jennifer Michaelson acquired 8,000 Cullinan Therapeutics common shares through option exercises. The filing shows an exercise of stock options resulting in 8,000 shares at a stated exercise price of $4.30 per share, classified as a derivative exercise or conversion transaction.

Why did Jennifer Michaelson sell Cullinan Therapeutics (CGEM) shares according to the Form 4 footnotes?

The footnotes explain that part of Jennifer Michaelson’s share sales were made to cover personal income tax obligations upon vesting of restricted stock units. They also state that the transactions were carried out under a pre-established Rule 10b5-1 trading plan.

Was Jennifer Michaelson’s Cullinan Therapeutics (CGEM) trade under a Rule 10b5-1 plan?

Yes. The disclosure states the transactions were effected under a trading plan established pursuant to Rule 10b5-1 on August 7, 2025. Such plans pre-schedule trades, creating a structured framework for insider transactions in company shares.

What is Jennifer Michaelson’s role at Cullinan Therapeutics (CGEM) in this insider filing?

In this insider transaction report, Jennifer Michaelson is identified as Cullinan Therapeutics’ Chief Scientific Officer. The Form 4 lists her as an officer of the company and reports equity transactions in the company’s common stock and related stock options.