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

Rhea-AI Filing Summary

David Charles Lubner, a director of CARGO Therapeutics, Inc. (CRGX), reported the disposition of a stock option covering 25,000 shares on 08/19/2025. The Form 4 shows the option had an exercise price of $4.35 and was reported as disposed (D), leaving 0 derivative securities beneficially owned after the transaction. The footnotes state the disposition occurred pursuant to the Agreement and Plan of Merger dated July 7, 2025, under which a tender offer completed on August 18, 2025 offered $4.379 per share in cash plus one non-transferable Contingent Value Right (CVR) per share. The filing explains that outstanding options were vested and then, if not exercised, canceled and converted into cash and CVRs consistent with the merger terms.

Positive

• Merger completed with a tender offer providing $4.379 per share plus one CVR, giving option holders a defined cash and contingent-right outcome
• Options fully vested prior to conversion, ensuring holders received the merger consideration rather than forfeiting unvested awards

Negative

• Director's derivative position reduced to zero (25,000 options reported disposed), eliminating that form of insider equity exposure
• Options were canceled and converted under merger terms, which could be less valuable than retained equity if future upside materializes

Insights

Financial Analyst

TL;DR: Director reported cancellation/disposition of 25,000 options for cash plus CVR as part of a completed merger/tender offer.

The Form 4 discloses a material insider change: a director's derivative position of 25,000 options with a $4.35 strike was reported disposed on 08/19/2025 and shows zero derivative holdings afterward. The filing explicitly ties the disposition to a Merger Agreement and a tender offer that paid $4.379 per share plus a CVR, and states options were converted/cash-settled under merger terms. For investor analysis, this is a corporate-control event that removes previously outstanding director-held options and replaces potential equity exposure with cash and contingent rights, which can affect post‑transaction ownership and incentive alignment.

M&A Specialist

TL;DR: Transaction reflects standard option treatment in an acquisition: vesting, cash settlement and issuance of CVRs per merger agreement.

The disclosure is consistent with common M&A mechanics: a merger/tender offer closed on August 18, 2025, offering $4.379 per share plus one CVR. The Form 4 shows that unexercised options became vested and were then canceled and converted into cash amounts equal to the excess of the cash offer over strike, plus CVRs per underlying share. The director’s derivative holdings were eliminated (0 remaining), indicating full contract-level treatment rather than retention of equity instruments. This is a material corporate event but follows the explicit terms disclosed rather than indicating contested or unusual treatment.

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

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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^*

Lubner David Charles

(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 David Lubner	08/19/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What did David Lubner report on Form 4 for CRGX?

He reported the disposition of a 25,000-share stock option on 08/19/2025, leaving 0 derivative securities beneficially owned.

Why were the options disposed according to the filing?

The options were disposed pursuant to the Agreement and Plan of Merger dated July 7, 2025, following a tender offer and merger consummated by Concentra Biosciences entities.

What cash consideration and additional rights were offered per share in the tender?

$4.379 per share in cash plus one non-transferable Contingent Value Right (CVR) per share, as stated in the filing.

What happened to outstanding options under the merger terms?

Outstanding options vested and then, 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, per the Form 4 footnotes.

Did the filing state the option exercise price?

Yes: the reported stock option had an exercise price of $4.35.