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

Rhea-AI Filing Summary

Cartesian Therapeutics, Inc. (RNAC)11/18/2025. The director gifted 20,000 shares of common stock, reported with transaction code G at a stated price of $0 per share, which is typical for a charitable or family transfer. After this transaction, the director held 53,533 shares directly. Additional shares are reported as indirectly held, including 383,796 shares in a trust for the benefit of the director’s spouse and children, as well as other trusts and custodial accounts for family members.

11/19/2025 - 06:35 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

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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^*

Singer Michael

(Last) (First) (Middle)

C/O CARTESIAN THERAPEUTICS, INC.

7495 NEW HORIZON WAY

(Street)

FREDERICK MD 21703

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Cartesian Therapeutics, Inc. [ RNAC ]

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)
11/18/2025

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
Common Stock	11/18/2025		G		20,000	D	$0	53,533	D
Common Stock								383,796	I	by trust(1)
Common Stock								56,719	I	by trust(2)
Common Stock								7,127	I	by trust(3)
Common Stock								14,788	I	by spouse(4)
Common Stock								96,219	I	as custodian(5)
Common Stock								96,219	I	as custodian(6)

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. Shares are held in a trust for the benefit of the reporting person's spouse and children. The reporting person's spouse is a trustee of the trust.

2. Shares are held in a trust for which the reporting person is a beneficiary. The reporting person is a trustee of the trust.

3. Shares are held in a trust for which the reporting person is a beneficiary. The reporting person's spouse is a trustee of the trust.

4. Shares are held by the reporting person's spouse.

5. The shares are held for LS, the child of the reporting person, through a custodial account established pursuant to the Uniform Transfer to Minors Act ("UTMA") for which the reporting person serves as custodian.

6. The shares are held for SS, the child of the reporting person, through a custodial account established pursuant to the UTMA for which the reporting person serves as custodian.

Remarks:

	/s/ Matthew Bartholomae, Attorney-in-Fact for Michael Singer	11/19/2025
	** 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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