X0609 4 2026-09-24 0001907108 Lexeo Therapeutics, Inc. LXEO 0001995218 Townsend Richard Nolan false C/O LEXEO THERAPEUTICS, INC. 345 PARK AVENUE SOUTH, FLOOR 6 NEW YORK NY 10010 true true false false Chief Executive Officer 0 Common Stock 2026-09-14 5 A 0 2306 2.644 A 376778 D Stock Option (right to buy) 3.39 2026-09-24 4 A 0 145500 0 A 2036-09-23 Common Stock 145500 145500 D The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the Lexeo Therapeutics, Inc. 2023 Employee Stock Purchase Plan. This transaction is exempt under both Rule 16b-3(c) and Rule 16b-3(d). Includes 242,911 Restricted Stock Units. 25% of the shares underlying the option vest and become exercisable on September 24, 2027, and 1/48th of the shares underlying the option shall vest in monthly installments thereafter, subject to the Reporting Person's continuous service. /s/ Youjin Choi, Attorney-in-Fact 2026-09-28