[Form 4] Cullinan Therapeutics, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Cullinan Therapeutics director Doyle Mittie received a stock option award to purchase 79,456 shares of the company’s common stock. The grant has an exercise price of $7.03 per share and was transacted on 08/07/2025. The option vests in three equal installments: one-third on each of the first, second and third anniversaries of the grant date, conditioned on the Reporting Persons continued service as a director.

The option is held directly, the reported number of derivative securities beneficially owned after the transaction is 79,456, and the option has an indicated expiration date of 08/07/2035.

Positive

• Grant terms are explicit: 79,456 options at an exercise price of $7.03 are clearly disclosed
• Vesting tied to continued service: one-third vests each anniversary, aligning vesting to future board service

Negative

• Potential dilution: exercise could create up to 79,456 additional shares
• Materiality unclear: filing does not state total outstanding shares or percentage impact of the award

Insights

Securities Analyst

TL;DR: Director awarded 79,456 options at $7.03; vesting over three years; 10-year term to 08/07/2035.

The filing shows a single derivative transaction: a stock option to purchase 79,456 shares at an exercise price of $7.03, reported on 08/07/2025. Vesting is explicit: one-third of the shares vest on each of the first three anniversaries of the grant date, contingent on continued board service. The option is recorded as directly beneficially owned. The filing does not disclose outstanding share count or percentage ownership, so the absolute or percentage dilution from exercise cannot be assessed from this document alone.

Corporate Governance Expert

TL;DR: Routine director equity award with time-based vesting; materiality cannot be judged from this filing alone.

The disclosure documents a time-based equity award to a director with explicit vesting conditions tied to continued service and a stated expiration date. These elements are standard for director compensation plans. The report provides the exact number of underlying shares (79,456), exercise price ($7.03), and vesting schedule, but omits context such as the grants relation to total outstanding shares or plan limits, preventing a full assessment of investor impact from this filing alone.

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

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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^*

Doyle Mittie

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
08/07/2025

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
Stock Option (Right to Buy)	$7.03	08/07/2025		A		79,456		(1)	08/07/2035	Common Stock	79,456	$0.00	79,456	D

Explanation of Responses:

1. The option represents a right to purchase a total of 79,456 shares of the Issuer's common stock, which shall vest as to one-third of the shares underlying the option on each of the first, second and third anniversaries of the grant date of the award, subject to the Reporting Person's continued service as a director on each such vesting date.

	/s/ Jacquelyn Sumer, Attorney-in-Fact	08/08/2025
	** 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 did Cullinan (CGEM) disclose in this Form 4?

The filing reports that director Doyle Mittie was granted a stock option to buy 79,456 shares at an exercise price of $7.03, with vesting described in the filing.

When was the option transaction reported for CGEM?

The transaction date listed in the filing is 08/07/2025.

How does the option vest according to the filing?

The option vests one-third of the shares on each of the first, second and third anniversaries of the grant date, subject to continued service as a director.

What is the exercise price and expiration date of the option in the filing?

The option has an exercise price of $7.03 and an indicated expiration date of 08/07/2035.

Does the Form 4 show the percentage ownership impact of this grant?

No. The filing lists the number of options (79,456) but does not provide total outstanding shares or percentage impact.