X0609 4 2026-07-01 0 0001869105 BridgeBio Oncology Therapeutics, Inc. BBOT 0001599214 Chen Bihua false C/O HELIX ACQUISITION CORP. II 200 CLARENDON STREET, 52ND FLOOR BOSTON MA 02116 1 0 1 0 0 Common Stock 2026-07-01 4 J 0 4528186 0.00 D 0 I Via Helix Holdings II LLC Common Stock 2026-07-01 4 J 0 2692459 0.00 A 4879995 I Via Fund III Common Stock 2026-07-01 4 J 0 1704862 0.00 A 5010332 I Via Fund V Common Stock 2026-07-01 4 J 0 130865 0.00 A 6083221 I Via Master Fund Common Stock 1905046 I Via Fund IV Represents a pro rata distribution to the members of Helix Holdings II LLC (the "Sponsor") for no consideration. Cormorant Private Healthcare Fund III, LP ("Fund III"), which is an investment vehicle managed by Cormorant Asset Management, LP ("CAM"), is a member of the Sponsor and received such shares in a pro rata distribution by the Sponsor for no consideration. Cormorant Private Healthcare Fund V, LP ("Fund V"), which is an investment vehicle managed by CAM, is a member of the Sponsor and received such shares in a pro rata distribution by the Sponsor for no consideration. Cormorant Global Healthcare Master Fund, LP ("Master Fund"), which is an investment vehicle managed by CAM, is a member of the Sponsor and received such shares in a pro rata distribution by the Sponsor for no consideration. Sponsor is the record holder of the securities reported herein. Fund III, Fund V, and Master Fund are the members of Sponsor. Bihua Chen is the manager of Sponsor and has voting and investment discretion with respect to the shares held of record by Sponsor. Each of Fund III, Fund V, Master Fund and Ms. Chen disclaims any beneficial ownership of the securities held by Sponsor other than to the extent of any pecuniary interest she or it may have therein, directly or indirectly. CAM serves as the investment manager to Fund III, Cormorant Private Healthcare Fund IV, LP ("Fund IV"), Fund V, and Master Fund (collectively, the "Cormorant Funds"). Cormorant Private Healthcare GP III, LLC ("GP III") is the general partner of Fund III; Cormorant Private Healthcare GP IV, LLC ("GP IV") is the general partner of Fund IV; Cormorant Private Healthcare GP V, LLC ("GP V") is the general partner of Fund V; and Cormorant Global Healthcare GP, LLC ("Global GP") is the general partner of the Master Fund. Bihua Chen serves as the managing member of GP III, GP IV, GP V, and Global GP, and as the general partner of CAM. Accordingly, Ms. Chen has voting and investment discretion with respect to the shares held by each of the Cormorant Funds and CAM. Ms. Chen disclaims any beneficial ownership of the securities held by each of the Cormorant Funds other than to the extent of any pecuniary interest she may have therein, directly or indirectly. Ms. Chen serves on the Board of Directors of the Issuer. Sponsor and the Cormorant Funds may be deemed to be directors by deputization as a result of the service of Ms. Chen. /s/ Bihua Chen 2026-07-06