FMR LLC (RNAC) holds 799,743 shares, 3.0% stake — Amendment No. 4

Rhea-AI Filing Summary

CARTESIAN THERAPEUTICS INC ownership update: institutional investor FMR LLC reports beneficial ownership of 799,743 shares of Common Stock, representing 3.0% of the class as of 03/31/2026. The filing also lists Abigail P. Johnson with dispositive power over the same 799,743 shares.

The filing is an Amendment No. 4 to a Schedule 13G/A and includes a reference to a 13d-1(k) agreement in Exhibit 99 and a power of attorney incorporated by reference.

Key Figures

Beneficial ownership: 799,743 shares Percent of class: 3.0% Sole voting power: 797,853 shares +3 more

6 metrics

Beneficial ownership 799,743 shares Amount beneficially owned (Item 4)

Percent of class 3.0% Percent of class as reported (Item 4)

Sole voting power 797,853 shares Sole voting power reported on cover page

Sole dispositive power 799,743 shares Sole dispositive power reported on cover page

Reporting date 03/31/2026 Cover page date

CUSIP 816212302 Class identifier on cover page

Key Terms

Schedule 13G/A, Beneficially owned, Sole dispositive power, 13d-1(k) agreement, +1 more

5 terms

Schedule 13G/A regulatory

"Amendment No. 4 ) CARTESIAN THERAPEUTICS INC COMMON STOCK"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

Beneficially owned financial

"Item 4. | Ownership (a) | Amount beneficially owned: 799743.00"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Sole dispositive power regulatory

"7 | Sole Dispositive Power 799,743.00"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

13d-1(k) agreement regulatory

"Exhibit 99 for 13d-1(k) (1) agreement."

Power of Attorney legal

"Duly authorized under Power of Attorney effective as of April 13, 2026"

A power of attorney is a legal document that allows one person to make decisions and act on behalf of another person, often in financial or legal matters. It’s like giving someone a trusted helper or agent the authority to handle important tasks if you are unable to do so yourself. This matters to investors because it can impact how their assets are managed or transferred if they become unable to oversee their affairs.

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

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Accepted by SEC EDGAR 05/06/2026 - 11:06 AM Learn about SEC filing dates

FAQ

What stake does FMR LLC report in CARTESIAN THERAPEUTICS (RNAC)?

FMR LLC reports beneficial ownership of 799,743 shares, representing 3.0% of CARTESIAN THERAPEUTICS common stock as of 03/31/2026. The filing appears as Amendment No. 4 to a Schedule 13G/A and lists voting/dispositive powers on the cover page.

Who is listed as having dispositive power over RNAC shares in this filing?

The filing lists Abigail P. Johnson with sole dispositive power over 799,743 shares. Signatures show transactions filed by an authorized representative under a power of attorney dated April 13, 2026, and signed May 5, 2026.

What date and CUSIP are shown for the RNAC Schedule 13G/A amendment?

The cover data shows the date 03/31/2026 and CUSIP 816212302 for CARTESIAN THERAPEUTICS common stock. The filing is identified as Amendment No. 4 to the Schedule 13G/A and references Exhibit 99 for a 13d-1(k) agreement.

Does the Schedule 13G/A indicate any holder over 5% of RNAC?

No single other person's interest is reported as over 5%. The filing states one or more other persons have rights to dividends or sale proceeds, but none exceed 5.0% of outstanding common stock per the disclosure.

Where is FMR LLC's principal business address listed in the RNAC filing?

The filing lists FMR LLC's principal business office as 245 Summer Street, Boston, Massachusetts 02210. That address appears in Item 2 as the registrant's principal business office for the Schedule 13G/A amendment.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 4)

CARTESIAN THERAPEUTICS INC

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

816212302

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 816212302

1

Names of Reporting Persons

FMR LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 797,853.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 799,743.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

799,743.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

3.0 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 816212302

1

Names of Reporting Persons

Abigail P. Johnson

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 799,743.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

799,743.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

3.0 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: CARTESIAN THERAPEUTICS INC
(b)	Address of issuer's principal executive offices: 7495 NEW HORIZON WAY,FREDERICK,MD,USA,21703
Item 2.
(a)	Name of person filing: FMR LLC
(b)	Address or principal business office or, if none, residence: 245 Summer Street, Boston, Massachusetts 02210
(c)	Citizenship: Not applicable
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP No.: 816212302
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 799743.00
(b)	Percent of class: 3.0 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Please see the responses to Items 5 and 6 on the cover page.
	(ii) Shared power to vote or to direct the vote: 0.00
	(iii) Sole power to dispose or to direct the disposition of: 799743.00
	(iv) Shared power to dispose or to direct the disposition of: 0.00
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. One or more other persons are known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the COMMON STOCK of CARTESIAN THERAPEUTICS INC. No one other person's interest in the COMMON STOCK of CARTESIAN THERAPEUTICS INC is more than five percent of the total outstanding COMMON STOCK.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. See attached Exhibit 99.
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

FMR LLC

Signature:	Richard Bourgelas
Name/Title:	Duly authorized under Power of Attorney effective as of April 13, 2026, by and on behalf of FMR LLC and its direct and indirect subsidiaries*
Date:	05/05/2026

Abigail P. Johnson

Signature:	Richard Bourgelas
Name/Title:	Duly authorized under Power of Attorney effective as of April 13, 2026, by and on behalf of Abigail P. Johnson*
Date:	05/05/2026

Comments accompanying signature: *This power of attorney is incorporated herein by reference to Exhibit 24 to the Schedule 13G filed by FMR LLC on April 29,2026, accession number: 0000315066-26-000738.

Exhibit Information

Please see Exhibit 99 for 13d-1(k) (1) agreement.