[SCHEDULE 13G] Cabaletta Bio, Inc. SEC Filing

Rhea-AI Filing Summary

Cormorant Asset Management, LP and Bihua Chen reported beneficial ownership of 5,000,000 shares of Cabaletta Bio common stock, equal to 5.47% of the outstanding class. The filing attributes sole voting and dispositive power of these shares as 0 and shared voting and dispositive power as 5,000,000. The shares are held by the Cormorant Funds and the filing identifies Cormorant Global Healthcare Master Fund, LP as having rights to more than 5% of the referenced shares. The ownership percentage is calculated using 91,465,233 shares outstanding as reported as of August 1, 2025. The filers certify the shares were acquired and are held in the ordinary course of business and not for the purpose of changing control, and they submitted a joint filing statement accepting responsibility for their portions of the disclosure.

Positive

• Reported beneficial ownership of 5,000,000 shares, representing 5.47% of Cabaletta Bio's outstanding common stock
• Disclosure identifies holdings as held by Cormorant Funds and names Cormorant Global Healthcare Master Fund, LP as holding rights to more than 5% of the referenced shares
• Filers certify shares were acquired and are held in the ordinary course of business and not to change control

Negative

• None.

Insights

Securities Analyst

TL;DR: Cormorant discloses a 5.47% position (5,000,000 shares) in Cabaletta Bio, held by Cormorant Funds with shared voting/dispositive power.

The Schedule 13G shows a material passive stake above the 5% reporting threshold: 5,000,000 shares (5.47%) of common stock. The filing attributes no sole voting or dispositive power and records shared voting and dispositive power of 5,000,000 shares, reflecting ownership through the Cormorant Funds rather than direct individual control. The filing also names Cormorant Global Healthcare Master Fund, LP as a fund with rights to more than 5% of the referenced shares. Filers certify ordinary-course holdings and deny an intent to change control.

Corporate Governance Expert

TL;DR: Joint filing by adviser and managing member reports shared control of 5,000,000 shares and includes a joint filing statement accepting responsibility.

The report is a joint Schedule 13G filed on behalf of Cormorant Asset Management, LP and Bihua Chen, documenting shared voting/dispositive authority rather than sole control. The inclusion of a joint filing statement clarifies allocation of filing responsibility among the reporting persons. The disclosure cites the exact outstanding share base used for the percentage calculation (91,465,233 shares) and contains a certification that holdings are ordinary-course and not acquired to influence control, which is relevant for governance assessments of intent and potential activist behavior.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Cabaletta Bio, Inc.

(Name of Issuer)

Common Stock, par value $0.00001 per share

(Title of Class of Securities)

12674W109

(CUSIP Number)

06/30/2025

(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)

SCHEDULE 13G

CUSIP No. 12674W109

1

Names of Reporting Persons

Cormorant Asset Management, LP

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 0.00
6	Shared Voting Power 5,000,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 5,000,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,000,000.00

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)

5.47 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP No. 12674W109

1

Names of Reporting Persons

Bihua Chen

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 5,000,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 5,000,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,000,000.00

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)

5.47 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Cabaletta Bio, Inc.
(b)	Address of issuer's principal executive offices: 2929 Arch Street, Suite 600, Philadelphia, PA 19104
Item 2.
(a)	Name of person filing: Cormorant Asset Management, LP Bihua Chen This statement is filed by (i) Cormorant Asset Management, LP, a Delaware limited partnership, and the investment adviser to certain funds (the "Cormorant Funds"), with respect to the shares directly held by the Cormorant Funds and (ii) Bihua Chen with respect to the shares directly held by the Cormorant Funds. The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons." The filing of this statement should not be construed as an admission that any of the foregoing persons or any Reporting Person is, for the purposes of Section 13 of the Act, the beneficial owner of the shares reported herein.
(b)	Address or principal business office or, if none, residence: 200 Clarendon Street, 52nd Floor Boston, MA 02116
(c)	Citizenship: Cormorant Asset Management, LP - Delaware Bihua Chen - United States
(d)	Title of class of securities: Common Stock, par value $0.00001 per share
(e)	CUSIP No.: 12674W109
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: 5,000,000
(b)	Percent of class: 5.47%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 5,000,000
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 5,000,000 The percentages reported herein with respect to the Reporting Persons' holdings are calculated based upon a statement in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025 as filed with the Securities and Exchange Commission on August 7, 2025, that there were 91,465,233 shares of Common Stock of the Issuer outstanding as of August 1, 2025.
Item 5.	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. See Item 2. The Cormorant Funds have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the shares reported herein. Cormorant Global Healthcare Master Fund, LP, a Cormorant Fund, has the right to receive or the power to direct the receipt of dividends or the proceeds from the sale of more than 5% of the shares.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
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.

Cormorant Asset Management, LP

Signature:	/s/ Bihua Chen
Name/Title:	Bihua Chen, Managing Member
Date:	08/14/2025

Bihua Chen

Signature:	/s/ Bihua Chen
Name/Title:	Bihua Chen
Date:	08/14/2025

Exhibit Information

JOINT FILING STATEMENT PURSUANT TO RULE 13d-1(k) The undersigned acknowledge and agree that the foregoing statement on SCHEDULE 13G, is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on SCHEDULE 13G, shall be filed on behalf of each of the undersigned without the necessity of filing additional joint acquisition statements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning her or it contained therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that she or it knows or has reason to believe that such information is inaccurate. Dated: August 14, 2025 Cormorant Asset Management, LP By: Cormorant Asset Management GP, LLC its General Partner By: /s/ Bihua Chen Bihua Chen, Managing Member Bihua Chen By: /s/ Bihua Chen Bihua Chen

FAQ

What stake in Cabaletta Bio (CABA) was disclosed in this Schedule 13G?

5,000,000 shares, representing 5.47% of the outstanding common stock.

Who filed the Schedule 13G for CABA?

Cormorant Asset Management, LP and Bihua Chen filed jointly.

Does the filer have sole voting or dispositive power over the disclosed shares?

No; the filing reports 0 sole voting power and 5,000,000 shared voting power, and similarly 0 sole dispositive power and 5,000,000 shared dispositive power.

How was the ownership percentage calculated for the filing?

Using 91,465,233 shares outstanding as reported by the issuer as of August 1, 2025, yielding 5.47% for 5,000,000 shares.

Are the shares held on behalf of a fund or other persons?

Yes; the shares are held by the Cormorant Funds, and Cormorant Global Healthcare Master Fund, LP is identified as having rights to more than 5% of the shares referenced.

Did the filers state an intent to influence control of Cabaletta Bio?

No; the certifications state the securities were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control.