CABA

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of The Securities Exchange Act of 1934

June 1, 2022

Date of Report (Date of earliest event reported)

CABALETTA BIO, INC.

(Exact name of Registrant as Specified in its Charter)

(267) 759-3100

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Cabaletta Bio, Inc., a Delaware corporation (the “Company”) held its Annual Meeting of Stockholders (the “Annual Meeting”) on June 1, 2022. As of April 4, 2022, the record date for the Annual Meeting, there were 25,064,629 outstanding shares of the Company’s voting common stock. The Company’s stockholders voted on the following matters, which are described in detail in the Company’s Definitive Proxy Statement filed with the U.S. Securities and Exchange Commission on April 21, 2022: (i) to elect two directors, Steven Nichtberger, M.D. and Mark Simon, MBA, as Class III directors of the Company to serve for a three-year term expiring at the Company’s 2025 annual meeting of stockholders and until their successor has been duly elected and qualified, subject to their earlier death, resignation or removal (“Proposal 1”) and (ii) to ratify the appointment of Ernst & Young LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2022 (“Proposal 2”).

The Company’s stockholders approved the Class III director nominees, Steven Nichtberger, M.D. and Mark Simon, MBA, recommended for election in Proposal 1 at the Annual Meeting. The votes cast at the Annual Meeting were as follows:

The Company’s stockholders ratified the appointment of Ernst & Young LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2022, recommended for ratification in Proposal 2 at the Annual Meeting. The votes cast at the Annual Meeting were as follows:

No other matters were submitted to or voted on by the Company’s stockholders at the Annual Meeting.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized.