Michael Singer - 02 Jan 2026 Form 4 Insider Report for Cartesian Therapeutics, Inc. (RNAC)

Role: Director
Signature: /s/ Matthew Bartholomae, Attorney-in-Fact for Michael Singer
Issuer symbol: RNAC
Transactions as of: 02 Jan 2026
Net transactions value: $0
Form type: 4
Filing time: 06 Jan 2026, 16:18:19 UTC
Previous filing: 19 Nov 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Singer Michael	Director	C/O CARTESIAN THERAPEUTICS, INC., 7495 NEW HORIZON WAY, FREDERICK	/s/ Matthew Bartholomae, Attorney-in-Fact for Michael Singer	06 Jan 2026	0002000122

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	RNAC	Common Stock	Award	$0	+2,600	+4.9%	$0.000000	56,133	02 Jan 2026	Direct	F1
holding	RNAC	Common Stock						383,796	02 Jan 2026	by trust	F2
holding	RNAC	Common Stock						56,719	02 Jan 2026	by trust	F3
holding	RNAC	Common Stock						7,127	02 Jan 2026	by trust	F4
holding	RNAC	Common Stock						14,788	02 Jan 2026	by spouse	F5
holding	RNAC	Common Stock						96,219	02 Jan 2026	as custodian	F6
holding	RNAC	Common Stock						96,219	02 Jan 2026	as custodian	F7

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	RNAC	Stock Option (Right to Buy)	Award	$0	+7,800		$0.000000	7,800	02 Jan 2026	Common Stock	7,800	$6.76	Direct

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Each Restricted Stock Unit represents a contingent right to receive one share of common stock, which will vest in full on January 2, 2027.
F2	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.
F3	Shares are held in a trust for which the reporting person is a beneficiary. The reporting person is a trustee of the trust.
F4	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.
F5	Shares are held by the reporting person's spouse.
F6	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.
F7	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.