Cartesian Therapeutics (RNAC) director Michael Singer gifts 6,555 shares

Rhea-AI Filing Summary

Cartesian Therapeutics director Michael Singer reported a bona fide gift of 6,555 shares of Common Stock on March 13, 2026. The gift was made at no stated price and is classified as a non-market disposition rather than a sale.

After the gift, Singer directly holds 49,578 shares. He also reports additional indirect holdings in Cartesian Therapeutics through several trusts, a spouse account, and custodial accounts for his children under UTMA.

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)
03/13/2026

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	03/13/2026		G		6,555	D	$0	49,578	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	03/13/2026
	** 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.

FAQ

What insider transaction did Michael Singer report for Cartesian Therapeutics (RNAC)?

Michael Singer reported a bona fide gift of 6,555 shares of Cartesian Therapeutics Common Stock on March 13, 2026. The transaction is coded “G,” meaning it is a gift disposition, not an open-market sale or purchase, and carried a reported price of $0.00 per share.

How many Cartesian Therapeutics (RNAC) shares does Michael Singer own directly after this Form 4?

After the reported gift, Michael Singer directly owns 49,578 shares of Cartesian Therapeutics Common Stock. This figure reflects his direct holdings only; he also reports additional indirect ownership through trusts, his spouse, and custodial accounts for his children, all detailed as separate entries.

Were any Cartesian Therapeutics (RNAC) shares sold on the market in this Form 4?

No, the filing shows no open-market sales of Cartesian Therapeutics shares. The only transaction is a bona fide gift of 6,555 shares, reported with transaction code “G.” All other entries are holding lines describing post-transaction indirect ownership positions in various related accounts.

What indirect Cartesian Therapeutics (RNAC) holdings does Michael Singer report?

Michael Singer reports several indirect holdings, including 383,796 shares held by a trust benefiting his spouse and children, 56,719 shares in a trust where he is a beneficiary and trustee, 7,127 shares in another trust, 14,788 shares held by his spouse, and 96,219-share UTMA custodial accounts.

Does the Form 4 indicate any derivative securities for Cartesian Therapeutics (RNAC)?

The Form 4 derivative section is empty, indicating no derivative securities, such as options or warrants, are reported in this filing. All reported positions are in Cartesian Therapeutics Common Stock, split between direct ownership and several indirect holdings through trusts, spouse, and custodial accounts.