X0206 3 2019-10-24 0 0001759138 Cabaletta Bio, Inc. CABA 0001487989 Nichtberger Steven C/O CABALETTA BIO, INC. 2929 ARCH STREET, SUITE 600 PHILADELPHIA PA 19104 1 1 0 0 President & CEO Common Stock 726000 D Common Stock 363000 I By 2017 Nichtberger Family Trust Series A-1 Preferred Stock Common Stock 60483 D Stock Option (Right to Buy) 1.01 2028-10-28 Common Stock 279677 D The reporting person disclaims beneficial ownership of these securities, and the filing of this report is not an admission that the reporting person is the beneficial owner of these securities for purposes of Section 16 or for any other purpose. The Series A-1 Preferred Stock is convertible into shares of the Issuer's Common Stock on a one-for-1.5 basis. Upon the closing of the Issuer's initial public offering, all shares of Series A-1 Preferred Stock will convert into shares of Common Stock of the Issuer. The Series A-1 Preferred Stock has no expiration date. This option vests over four years, with 25% vesting on October 11, 2019, and the remaining shares vesting in 36 equal monthly installments thereafter. Exhibit 24 - Power of Attorney /s/ Steven Nichtberger 2019-10-24