X0609 4 2026-04-30 0002042347 Seaport Therapeutics, Inc. SPTX 0001820278 Torres Denice false SEAPORT THERAPEUTICS, INC. 101 SEAPORT BLVD., FLOOR 12 BOSTON MA 02210 true false false false false Common Stock 2026-05-04 4 C false 13406 A 13406 I By Denice M. Torres Revocable Trust Stock Option (Right to Buy) 18 2026-04-30 4 A false 12258 0 A 2036-04-29 Common Stock 12258 12258 D Series B Preferred Stock 2026-05-04 4 C false 42105 0 D Common Stock 13406 0 I By Denice M. Torres Revocable Trust Each share of Series B Preferred Stock (the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-one basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering on May 4, 2026 without payment of further consideration. The Preferred Stock had no expiration date. The Reporting Person disclaims beneficial ownership of such shares for purposes of Section 16 of the Exchange Act, except to the extent of her pecuniary interest therein, if any. This report shall not be deemed an admission that she is a beneficial owner of such shares for the purpose of Section 16 of the Exchange Act, or for any other purpose. The shares underlying this option shall vest in full on April 30, 2027, subject to the Reporting Person's continued service on such vesting date. /s/ Lana Gladstein, Attorney-in-Fact 2026-05-04