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

Rhea-AI Filing Summary

Jane Henderson, a director of CARGO Therapeutics, Inc. (CRGX), reported transactions on 08/19/2025 related to the company's merger. A stock option with a $4.35 exercise price covering 25,000 underlying shares was disposed of in connection with the Merger Agreement with Concentra Biosciences, LLC, following a tender offer and subsequent merger. Under the merger terms, each outstanding option that was not exercised prior to the effective time was converted into a cash payment equal to the excess of the cash offer over the option exercise price and one non-transferable contingent value right (CVR) per underlying share; options with exercise prices at or above the cash amount were canceled for no consideration. The filing shows 0 common shares owned following the reported transaction.

Insights

Financial Analyst

TL;DR: Insider option converted to cash plus CVRs in a merger, yielding a cash-equivalent payout tied to a $4.379 per-share offer and one CVR per share.

The reporting shows a director-level holder of a 25,000-share stock option with a $4.35 exercise price that was disposed of pursuant to the Merger Agreement with Concentra. Per the disclosed terms, unexercised options were converted into a cash amount equal to the excess of the $4.379 cash offer over the exercise price, and one CVR per underlying share. The filing reports 0 shares owned after the transaction, consistent with completion of the tender offer and merger process described.

Corporate Governance Expert

TL;DR: Director transactions reflect standard merger treatment of options: vesting, forced conversion, and cancellation where exercise price exceeds offer.

The Form 4 documents a director-level disclosure required by Section 16 following a corporate transaction. It confirms that options became vested and were treated under the Merger Agreement: exercised/converted into cash for the intrinsic value and coupled with CVRs, while options with exercise prices at or above the cash consideration were canceled. The signature by an attorney-in-fact is provided, and the filing cites the Merger and CVR Agreement as the controlling instruments.

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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X

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^*

Henderson Jane

(Last) (First) (Middle)

C/O CARGO THERAPEUTICS, INC.

835 INDUSTRIAL ROAD, SUITE 400

(Street)

SAN CARLOS CA 94070

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
CARGO Therapeutics, Inc. [ CRGX ]

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)
08/19/2025

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)	$4.35	08/19/2025		D			25,000	(1)(2)(3)	06/17/2035	Common Stock	25,000	(1)(2)(3)	0	D

Explanation of Responses:

1. Disposed of pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated as of July 7, 2025, by and among CARGO Therapeutics, Inc. (the "Issuer"), Concentra Biosciences, LLC ("Parent") and Concentra Merger Sub VII, Inc., a wholly owned subsidiary of Parent ("Merger Sub"). On August 18, 2025, Parent and Merger Sub completed a tender offer pursuant to the terms of the Merger Agreement for all outstanding shares of common stock of the Issuer (each, a "Share") for an offer price of (i) $4.379 per Share in cash (the "Cash Amount"), and (ii) one non-transferable contractual contingent value right (each, a "CVR"), subject to and in accordance with the terms of the Contingent Value Rights Agreement (the "CVR Agreement"), in each case, without interest, and subject to any applicable withholding taxes (the Cash Amount plus one CVR, collectively, the "Offer Price"). [continues to Footnote 2]

2. [continues from Footnote 1] Merger Sub thereafter merged with and into the Issuer, with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent (the "Merger"). As of immediately prior to and conditioned upon the effective time of the Merger, pursuant to the Merger Agreement, each outstanding option to purchase Shares (each, an "Option") became fully vested and exercisable, and to the extent not exercised prior to the effective time of the Merger, was canceled and converted into the right to receive (a) an amount in cash (without interest and subject to deduction for any required withholding tax) equal to the product of (1) the excess, if any, of the Cash Amount over the exercise price per share of each such Option and (2) the number of Shares underlying such Option immediately prior to the effective time of the Merger [continues to Footnote 3]

3. [continues from Footnote 2] and (b) one CVR in respect of each Share underlying such Option; provided, however, that if the exercise price per Share of any Option was equal to or greater than the Cash Amount that was then outstanding it was canceled for no consideration.

	/s/ Halley Gilbert, as attorney-in-fact for Jane Henderson	08/19/2025
	** Signature of Reporting Person	Date
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