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

Rhea-AI Filing Summary

Reid M. Huber, a director of CARGO Therapeutics, Inc. (CRGX), reported on Form 4 that on 08/19/2025 he disposed of a stock option covering 25,000 shares. The option had an exercise price of $4.35 and is shown as a disposition in connection with the Merger Agreement dated July 7, 2025. The filing explains that Parent completed a tender offer and then merged with the issuer, and that outstanding options were treated per the Merger Agreement: fully vested and exercisable immediately prior to the merger and thereafter canceled and converted into a cash payment equal to the excess, if any, of the Cash Amount over the exercise price per share plus one contractual contingent value right (CVR) per underlying share. The reported transaction was signed by attorney-in-fact Halley Gilbert on 08/19/2025.

Positive

• Disposition occurred pursuant to a completed Merger Agreement, providing clear contractual treatment of options
• Insider reported timely on Form 4 dated 08/19/2025, improving transparency
• Options were treated to deliver cash plus CVRs, so option holders received consideration rather than being left unremedied

Negative

• None.

Insights

Financial Analyst

TL;DR: Insider options for 25,000 shares were cashed out in a completed merger, converting equity upside into cash plus contingent rights.

The Form 4 shows a director-level insider disposing of a 25,000-share option position on the merger effective date. The transaction follows the Merger Agreement where the offer price was $4.379 per share plus one CVR. Because the option exercise price is $4.35, the agreement provides for cash consideration for the in-the-money portion and issuance of CVRs in respect of each underlying share. This is a routine change-of-control treatment that realizes value for option holders and removes future equity dilution from these options.

Corporate Governance Expert

TL;DR: The Form 4 documents standard change-of-control option treatment and timely insider reporting following a merger.

The filing documents that options became fully vested and then were cancelled or converted per the Merger Agreement, and the director filed a Form 4 disclosing the disposition on the merger closing date. The report was executed by an attorney-in-fact, indicating delegated signing authority. This disclosure meets Section 16(a) reporting expectations and provides investors with transparency on insider holdings after the change of control.

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^*

Huber Reid M

(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 Reid Huber	08/19/2025
	** 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).
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FAQ

Who filed the Form 4 for CRGX?

Reid M. Huber, a director of CARGO Therapeutics, Inc., with the form signed by attorney-in-fact Halley Gilbert on 08/19/2025.

What was the transaction date and what was disposed?

The transaction date was 08/19/2025 and the filing reports disposition of a stock option for 25,000 shares (derivative security).

What were the terms applied to options in the merger?

Per the Merger Agreement, options became fully vested and exercisable immediately prior to the merger and, if not exercised, were canceled and converted into cash equal to the excess of the Cash Amount over the exercise price and one CVR per underlying share.

What was the Cash Amount and the option exercise price shown?

The filing states the Cash Amount was $4.379 per share and the option exercise price was $4.35.

Did the filing indicate any remaining ownership after the transaction?

The Table II reporting shows 0 shares of the underlying common stock beneficially owned following the reported transaction.