Cullinan CLO acquires 2,470 shares via ESPP

Cullinan Therapeutics Chief Legal Officer Jacquelyn L. Sumer acquired 2,470 shares of common stock at $8.60 per share through the company’s 2021 Employee Stock Purchase Plan.

Rhea-AI Filing Summary

Cullinan Therapeutics Chief Legal Officer Jacquelyn L. Sumer acquired 2,470 shares of common stock at $8.60 per share through the company’s 2021 Employee Stock Purchase Plan. The shares relate to the purchase period from January 1, 2026 through June 30, 2026 and were bought at 85% of the January 2, 2026 closing price. Following this routine ESPP transaction, she directly holds 130,559 shares of Cullinan Therapeutics common stock.

Insider Trade Summary

Grant/Award: 2,470 shares

Grant/Award 1 txn

Insider SUMER JACQUELYN L

Role Chief Legal Officer

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	2,470	$8.60	$21K

Holdings After Transaction: Common Stock — 130,559 shares (Direct)

Footnotes (2)

1. F1. 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. F2. 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

ESPP shares acquired: 2,470 shares Purchase price: $8.60 per share Holdings after transaction: 130,559 shares +2 more

5 metrics

ESPP shares acquired 2,470 shares Common Stock acquired on January 1–June 30, 2026 ESPP period

Purchase price $8.60 per share ESPP acquisition price for Cullinan Therapeutics common stock

Holdings after transaction 130,559 shares Direct ownership following ESPP acquisition

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

ESPP purchase period January 1–June 30, 2026 Offering period for reported ESPP purchase

Key Terms

Employee Stock Purchase Plan, ESPP, Rule 16b-3(c), closing price

4 terms

Employee Stock Purchase Plan financial

"acquisition of shares of the Issuer's common stock pursuant to the Issuer's 2021 Employee Stock Purchase Plan"

An employee stock purchase plan is a company program that lets workers buy shares through small payroll deductions, often at a discount to the market price and after a set offering period. Think of it like a workplace savings plan that turns into ownership: it encourages employees to share in the company’s success and can create predictable buying or selling of stock that investors watch because it affects supply, demand and employee incentives.

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.

closing price financial

"the shares were purchased based on 85% of the closing price of the Issuer's common stock on January 2, 2026"

FAQ

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

What insider transaction did Cullinan Therapeutics (CGEM) report for Jacquelyn L. Sumer?

Cullinan Therapeutics reported that Chief Legal Officer Jacquelyn L. Sumer acquired 2,470 shares of common stock at $8.60 per share. The shares were purchased through the 2021 Employee Stock Purchase Plan for the January 1 to June 30, 2026 offering period.

How many Cullinan Therapeutics (CGEM) shares does Jacquelyn L. Sumer hold after this Form 4?

After this transaction, Jacquelyn L. Sumer directly holds 130,559 shares of Cullinan Therapeutics common stock. This reflects the addition of 2,470 shares acquired under the company’s 2021 Employee Stock Purchase Plan during the January 1 to June 30, 2026 purchase period.

At what price were the new Cullinan Therapeutics (CGEM) shares acquired under the ESPP?

The new shares were acquired at $8.60 per share under Cullinan Therapeutics’ 2021 Employee Stock Purchase Plan. According to the filing, the purchase price equaled 85% of the closing price of the company’s common stock on January 2, 2026, consistent with ESPP terms.

What is the nature of Jacquelyn L. Sumer’s Cullinan Therapeutics (CGEM) transaction?

The transaction is an acquisition of shares as a grant or award, not an open-market buy. It reflects participation in Cullinan Therapeutics’ 2021 Employee Stock Purchase Plan and is exempt under Rule 16b-3(c), a rule that covers certain issuer-approved equity compensation transactions.

Which plan governed the recent share acquisition by Cullinan Therapeutics (CGEM)’s Chief Legal Officer?

The share acquisition was made under Cullinan Therapeutics’ 2021 Employee Stock Purchase Plan. The Form 4 specifies that the reported 2,470 shares were purchased pursuant to this ESPP for the purchase period from January 1, 2026 through June 30, 2026, at a plan-defined discounted price.

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

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Accepted by SEC EDGAR 07/02/2026 - 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).

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^*

SUMER JACQUELYN L

(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 Legal 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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	06/30/2026		A(1)		2,470	A	$8.6(2)	130,559	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

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	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)