Was the Cullinan Therapeutics (CGEM) CFO’s share acquisition an open-market purchase?

No. The acquisition was made through Cullinan Therapeutics’ 2021 Employee Stock Purchase Plan, not via an open-market trade. The filing notes the transaction is exempt under Rule 16b-3(c), reflecting a compensation-related purchase rather than a discretionary market buy.

Cullinan Therapeutics (CGEM) CFO adds 1,541 shares through ESPP purchase

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

Cullinan Therapeutics Chief Financial Officer Mary Kay Fenton reported an acquisition of company stock through the 2021 Employee Stock Purchase Plan. She obtained 1,541 shares of common stock for the purchase period from January 1, 2026 through June 30, 2026.

The shares were bought at $8.60 per share, based on 85% of the closing price on January 2, 2026, as provided under the ESPP. Following this routine, compensation-related transaction, she directly holds 127,921 shares of Cullinan Therapeutics common stock.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Fenton Mary Kay

Role Chief Financial Officer

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	1,541	$8.60	$13K

Holdings After Transaction: Common Stock — 127,921 shares (Direct, null)

Footnotes (1)

The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the Issuer's 2021 Employee Stock Purchase Plan (the "ESPP"), for the purchase period of January 1, 2026 through June 30, 2026. This transaction is also exempt under Rule 16b-3(c). In accordance with the ESPP, the shares were purchased based on 85% of the closing price of the Issuer's common stock on January 2, 2026.

Key Figures

Shares acquired: 1,541 shares Purchase price per share: $8.60 per share Post-transaction holdings: 127,921 shares +2 more

5 metrics

Shares acquired 1,541 shares Common stock acquired on June 30, 2026 via 2021 ESPP

Purchase price per share $8.60 per share ESPP purchase price for shares acquired June 30, 2026

Post-transaction holdings 127,921 shares Total common shares directly held by CFO after acquisition

ESPP discount basis 85% of closing price Based on 85% of January 2, 2026 closing stock price

Rule 16b-3(c) status Exempt transaction Acquisition reported as exempt under Rule 16b-3(c)

Key Terms

2021 Employee Stock Purchase Plan, ESPP, Rule 16b-3(c), Form 4

4 terms

2021 Employee Stock Purchase Plan financial

"The acquisition of shares was made pursuant to the Issuer's 2021 Employee Stock Purchase Plan (the "ESPP")."

ESPP financial

"In accordance with the ESPP, the shares were purchased based on 85% of the closing price."

An Employee Stock Purchase Plan (ESPP) is a company program that lets employees buy the company’s shares at a reduced price, usually by setting aside a small portion of their pay over time. It matters to investors because it encourages employees to own part of the business—like giving staff a discounted membership— which can boost commitment and performance, while also potentially increasing the number of shares available and affecting shareholder value.

Rule 16b-3(c) regulatory

"This transaction is also exempt under Rule 16b-3(c)."

An SEC rule that lets corporate insiders avoid automatic "short‑swing" profit recovery when they buy or sell their company’s stock under a pre‑approved, written plan that meets specific conditions. For investors, it matters because it clarifies when insider trades are treated as routine, reducing legal uncertainty and helping distinguish trades made for ordinary compensation or pre‑planned reasons from those that might signal opportunistic or timely insider advantage.

Form 4 regulatory

"Insider activity was disclosed in a Form 4 filing for the CFO."

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 07/02/2026 - 05:02 PM Accepted by SEC EDGAR 07/02/2026 - 05:00 PM

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^*

Fenton Mary Kay

(Last)

(First)

(Middle)

C/O CULLINAN THERAPEUTICS, INC.

ONE MAIN STREET, SUITE 1350

(Street)

CAMBRIDGE

MASSACHUSETTS

02142

(City)

(State)

(Zip)

UNITED STATES

(Country)

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 Financial Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/30/2026

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

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

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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	06/30/2026		A⁽¹⁾		1,541	A	$8.6⁽²⁾	127,921	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the Issuer's 2021 Employee Stock Purchase Plan (the "ESPP"), for the purchase period of January 1, 2026 through June 30, 2026. This transaction is also exempt under Rule 16b-3(c).

2. In accordance with the ESPP, the shares were purchased based on 85% of the closing price of the Issuer's common stock on January 2, 2026.

	/s/ Jacquelyn Sumer, Attorney-in-Fact	07/02/2026
	** 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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What insider transaction did Cullinan Therapeutics (CGEM) report for its CFO?

Cullinan Therapeutics reported that CFO Mary Kay Fenton acquired 1,541 shares of common stock through the company’s 2021 Employee Stock Purchase Plan for the January 1, 2026 to June 30, 2026 purchase period, as disclosed in a Form 4 insider transaction filing.

How many Cullinan Therapeutics (CGEM) shares did the CFO acquire and at what price?

The CFO acquired 1,541 shares of Cullinan Therapeutics common stock at $8.60 per share. The price was determined under the Employee Stock Purchase Plan, using 85% of the closing price of the company’s stock on January 2, 2026 as the purchase basis.

What is the source of the CFO’s new Cullinan Therapeutics (CGEM) shares?

The new shares came from Cullinan Therapeutics’ 2021 Employee Stock Purchase Plan. This plan allows eligible employees, including executives, to buy company stock at a discount, in this case using 85% of the January 2, 2026 closing price to set the purchase cost.

How many Cullinan Therapeutics (CGEM) shares does the CFO hold after this transaction?

After the reported acquisition, the CFO directly holds 127,921 shares of Cullinan Therapeutics common stock. This total includes the 1,541 shares purchased through the 2021 Employee Stock Purchase Plan for the six‑month period ending June 30, 2026.

What discount mechanism applied to the Cullinan Therapeutics (CGEM) ESPP shares?

Under the Employee Stock Purchase Plan, the shares were purchased based on 85% of the closing price of Cullinan Therapeutics common stock on January 2, 2026. This discount mechanism is typical of ESPP structures that offer employees stock at a reduced effective purchase price.