UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number: 001-41855 LEXEO THERAPEUTICS, INC. (Exact name of Registrant as specified in its Charter) (State or other jurisdiction of incorporation ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-41855 Lexeo Therapeutics, Inc. (Exact Name of Registrant as Specified in its Charter) | Delaware | 85-4012572 | | --- | --- | ...

Table of Contents As filed with the Securities and Exchange Commission on November 1, 2023 Registration No. 333-274777 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Amendment No. 2 to FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 Lexeo Therapeutics, Inc. (Exact name of registrant as specified in its charter) (State or other jurisdiction of incorporation or organization) Delaware 2836 85-4012572 (Primary Standard Industrial Classification Code Number) (I.R.S. Empl ...

Table of Contents As filed with the Securities and Exchange Commission on October 30, 2023 Registration No. 333-274777 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Amendment No. 1 to FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 Lexeo Therapeutics, Inc. (Exact name of registrant as specified in its charter) (State or other jurisdiction of incorporation or organization) Delaware 2836 85-4012572 (Primary Standard Industrial Classification Code Number) (I.R.S. Empl ...

Table of Contents As filed with the Securities and Exchange Commission on September 29, 2023 Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 Lexeo Therapeutics, Inc. (Exact name of registrant as specified in its charter) (State or other jurisdiction of incorporation or organization) Delaware 2836 85-4012572 (Primary Standard Industrial Classification Code Number) (I.R.S. Employer Identification No. ...