SC 13G/A: Cabaletta Bio, Inc.

AI Summary

SC 13G/A filing by Cabaletta Bio, Inc..

Risk Assessment

Risk Level: low

Key Financial Figures

• $0.00001 — ssuer) Voting Common Stock, par value $0.00001 per share (Title of Class of Securitie

Filing Documents

• p24-3076sc13ga.htm (SC 13G/A) — 69KB
• 0000902664-24-006409.txt ( ) — 71KB

(a)

Item 1(a). NAME OF ISSUER The name of the issuer is Cabaletta Bio, Inc. (the “ Company ”).

(b)

Item 1(b). ADDRESS OF ISSUER’S PRINCIPAL EXECUTIVE OFFICES The Company's principal executive offices are located at 2929 Arch Street, Suite 600, Philadelphia, Pennsylvania 19104.

(a)

Item 2(a). NAME OF PERSON FILING This statement is filed by: (i) Adage Capital Management, L.P., a Delaware limited partnership (“ ACM ”), as the investment manager of Adage Capital Partners, L.P., a Delaware limited partnership (“ ACP ”), with respect to the shares of Voting Common Stock directly held by ACP; (ii) Robert Atchinson (“ Mr. Atchinson ”), as (1) managing member of Adage Capital Advisors, L.L.C., a limited liability company organized under the laws of the State of Delaware (“ ACA ”), managing member of Adage Capital Partners GP, L.L.C., a limited liability company organized under the laws of the State of Delaware (“ ACPGP ”), general partner of ACP and (2) managing member of Adage Capital Partners LLC, a Delaware limited liability company (“ ACPLLC ”), general partner of ACM, with respect to the shares of Voting Common Stock directly held by ACP; and (iii) Phillip Gross (“ Mr. Gross ”), as (1) managing member of ACA, managing member of ACPGP and (2) managing member of ACPLLC, general partner of ACM, with respect to the shares of Voting Common Stock directly held by ACP. The foregoing persons are hereinafter sometimes collectively referred to as the “ Reporting Persons .” Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party. The filing of this statement should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of the securities reported herein.

(b)

Item 2(b). ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE The address of the business office of each of the Reporting Persons is 200 Clarendon Street, 52nd Floor, Boston, Massachusetts 02116.

(c)

Item 2(c). CITIZENSHIP ACM is a limited partnership organized under the laws of the State of Delaware. Messrs. Gross and Atchinson are citizens of the United States.

(d)

Item 2(d). TITLE OF CLASS OF SECURITIES Voting Common Stock, par value $0.00001 per share (the “ Voting Common Stock ”).

(e)

Item 2(e). CUSIP NUMBER 12674W109 CUSIP No. 12674W109 13G/A Page 6 of 8 Pages Item 3. IF THIS STATEMENT IS FILED PURSUANT TO Rules 13d-1(b), OR 13d-2(b) OR (c), CHECK WHETHER THE PERSON FILING IS A: (a) Broker or dealer registered under Section 15 of the Act; (b) Bank as defined in Section 3(a)(6) of the Act; (c) Insurance company as defined in Section 3(a)(19) of the Act; (d) Investment company registered under Section 8 of the Investment Company Act of 1940; (e) An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E); (f) An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F); (g) A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G); (h) A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act; (i) A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act; (j) A non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J); (k) Group, in accordance with Rule 13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J), please specify the type of institution: Not applicable . Item 4. The information required by Items 4(a) – (c) is set forth in Rows (5) – (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each such Reporting Person. The percentage set forth in this Schedule 13G/A is calculated based upon 48,291,469 shares of Voting Common Stock outstanding as of June 30, 2024, as reported in the Company's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2024, filed with the Securities and Exchange Commission on August 8, 2024. Item 5. Not applicable. Item 6. See Item 2(a). CUSIP No. 12674W

SIGNATURES

SIGNATURES After reasonable inquiry and to the best of his or its knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct. DATE: November 12, 2024 ADAGE CAPITAL MANAGEMENT, L.P. By: Adage Capital Partners LLC, its general partner /s/ Robert Atchinson Name: Robert Atchinson Title: Managing Member /s/ Robert Atchinson ROBERT ATCHINSON, individually /s/ Phillip Gross PHILLIP GROSS, individually

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