Cartesian CEO sells 23,766 shares in tax trade

Cartesian Therapeutics President and CEO Carsten Brunn reported a sale of company common stock.

Rhea-AI Filing Summary

Cartesian Therapeutics President and CEO Carsten Brunn reported a sale of company common stock. On 01/06/2026, he sold 23,766 shares of Cartesian Therapeutics, Inc. (RNAC) common stock at a price of $6.8197 per share.

According to the footnote, these shares were sold to satisfy withholding tax obligations upon the vesting of restricted stock units and to cover related broker fees. After this transaction, Brunn directly beneficially owned 323,530 shares of Cartesian Therapeutics common stock.

Insider Trade Summary

Net Seller: 23,766 shares

Net Sell 1 txn

Insider Brunn Carsten

Role President and CEO

Sold 23,766 shs ($162K)

Type	Security	Shares	Price	Value
Sale	Common Stock	23,766	$6.8197	$162K

Holdings After Transaction: Common Stock — 323,530 shares (Direct)

Footnotes (1)

1. F1. Shares sold to satisfy withholding tax obligations upon the vesting of restricted stock units and to cover related broker fees.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Cartesian Therapeutics (RNAC) report in this Form 4?

The filing reports that President and CEO Carsten Brunn sold 23,766 shares of Cartesian Therapeutics, Inc. common stock on 01/06/2026.

At what price were the Cartesian Therapeutics (RNAC) shares sold by the CEO?

The 23,766 shares of Cartesian Therapeutics common stock were sold at a price of $6.8197 per share.

Why did the Cartesian Therapeutics (RNAC) CEO sell 23,766 shares?

The footnote states the shares were sold to satisfy withholding tax obligations upon the vesting of restricted stock units and to cover related broker fees.

How many Cartesian Therapeutics (RNAC) shares does the CEO own after this transaction?

After the reported sale, Carsten Brunn beneficially owned 323,530 shares of Cartesian Therapeutics common stock.

Is the reported Cartesian Therapeutics (RNAC) insider transaction direct or indirect ownership?

The Form 4 indicates the CEO’s holdings after the transaction are held with direct ownership (coded "D").

What type of security was involved in the Cartesian Therapeutics (RNAC) Form 4 transaction?

The transaction involved common stock of Cartesian Therapeutics, Inc., reported in the non-derivative securities table.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 01/08/2026 - 04:20 PM Learn about SEC filing dates

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

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

Brunn Carsten

(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
X	Officer (give title below)		Other (specify below)
	President and CEO

3. Date of Earliest Transaction (Month/Day/Year)
01/06/2026

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	01/06/2026		S		23,766	D	$6.8197(1)	323,530	D

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 sold to satisfy withholding tax obligations upon the vesting of restricted stock units and to cover related broker fees.

Remarks:

	/s/ Matthew Bartholomae, Attorney-in-Fact for Carsten Brunn	01/08/2026
	** 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.
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