Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Mar. 20, 2020
Cover [Abstract]    
Document Type 10-K  
Amendment Flag false  
Document Period End Date Dec. 31, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus FY  
Trading Symbol CABA  
Entity Registrant Name CABALETTA BIO, INC.  
Entity Current Reporting Status Yes  
Entity Central Index Key 0001759138  
Entity Voluntary Filers No  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Well-known Seasoned Issuer No  
Entity Shell Company false  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Common Stock, Shares Outstanding   24,034,022
Entity Public Float   $ 144.0
Entity File Number 001-39103  
Entity Tax Identification Number 82-1685768  
Entity Address, Address Line One 2929 Arch Street  
Entity Address, Address Line Two Suite 600  
Entity Address, City or Town Philadelphia  
Entity Address, State or Province PA  
Entity Address, Postal Zip Code 19104  
City Area Code 267  
Local Phone Number 759-3100  
Entity Interactive Data Current Yes  
Title of 12(b) Security Common Stock, par value $0.00001 per share  
Security Exchange Name NASDAQ  
Entity Incorporation, State or Country Code DE  
Document Annual Report true  
Document Transition Report false  
Documents Incorporated by Reference


Part III of this Annual Report on Form 10-K incorporates by reference certain information from the registrant’s definitive Proxy Statement for its 2020 annual meeting of shareholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year end of December 31, 2019. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Form 10-K.