Cullinan CSO sells 8,000 shares after option exercise

Cullinan Therapeutics, Inc. Chief Scientific Officer Jennifer Michaelson reported option exercises and a share sale.

Rhea-AI Filing Summary

Cullinan Therapeutics, Inc. Chief Scientific Officer Jennifer Michaelson reported option exercises and a share sale. On the same day, she exercised stock options for 4,000 shares of common stock at $4.30 per share through a derivative exercise, and then sold 8,000 common shares in the open market at a weighted average price of $15.68 per share, with individual trades ranging from $15.38 to $16.31. The sale was made under a pre-established Rule 10b5-1 trading plan dated August 7, 2025. Following these transactions, she directly held 170,844 shares of common stock and 120,987 shares underlying stock options.

Insider Trade Summary

Exercise and sale activity reported; no spread calculated

Exercise and Sale 3 txns

Insider Michaelson Jennifer

Role Chief Scientific Officer

Sold 8,000 shs ($125K)

Approx. gross sale proceeds $125K

Approx. exercise cost $17K

Type	Security	Shares	Price	Value
Exercise	Stock Option (Right to Buy)	4,000	$0.00	$0.00
Exercise	Common Stock	4,000	$4.30	$17K
Sale	Common Stock	8,000	$15.68	$125K

Holdings After Transaction: Stock Option (Right to Buy) — 120,987 contracts (Direct); Common Stock — 170,844 shares (Direct)

Footnotes (3)

1. F1. Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 on August 7, 2025.
2. F2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $15.38 to $16.31. The Reporting Person undertakes to provide to the Issuer, any shareholder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
3. F3. 25% of the shares vested on July 4, 2020, and the remaining shares vested in 36 equal monthly installments thereafter.

FAQ

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

Cullinan Therapeutics reported that Chief Scientific Officer Jennifer Michaelson exercised options for 4,000 shares at $4.30 and sold 8,000 common shares at a weighted average price of $15.68. These trades occurred on March 5, 2026 under a pre-arranged Rule 10b5-1 plan.

How many Cullinan Therapeutics (CGEM) shares did the CSO sell and at what price?

Jennifer Michaelson sold 8,000 shares of Cullinan Therapeutics common stock at a weighted average price of $15.68 per share. According to the filing, the trades occurred in multiple transactions at prices ranging from $15.38 to $16.31 on March 5, 2026.

Were the Cullinan Therapeutics (CGEM) insider trades made under a Rule 10b5-1 plan?

Yes. The filing states the transactions were effected under a trading plan established pursuant to Rule 10b5-1 on August 7, 2025. Such plans allow insiders to pre-schedule trades, providing structure and reducing concerns about trading on material nonpublic information.

How many Cullinan Therapeutics (CGEM) shares does the CSO hold after these transactions?

After the reported transactions, Jennifer Michaelson directly held 170,844 shares of Cullinan Therapeutics common stock. She also held 120,987 shares underlying stock options following the option exercise of 4,000 shares described in the Form 4 filing.

What options did the Cullinan Therapeutics (CGEM) CSO exercise in this Form 4?

The CSO exercised stock options covering 4,000 shares of Cullinan Therapeutics common stock at an exercise price of $4.30 per share. A related footnote explains that 25% of these option shares vested on July 4, 2020, with the remainder vesting in 36 equal monthly installments thereafter.

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Accepted by SEC EDGAR 03/09/2026 - 05:00 PM 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).

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)
03/05/2026

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	03/05/2026		M		4,000	A	$4.3	178,844	D
Common Stock	03/05/2026		S(1)		8,000	D	$15.68(2)	170,844	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	03/05/2026		M			4,000	(3)	10/28/2030	Common Stock	4,000	$0	120,987	D

Explanation of Responses:

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

2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $15.38 to $16.31. The Reporting Person undertakes to provide to the Issuer, any shareholder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

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	03/09/2026
	** 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.