X0609 4 2026-05-07 0002012593 Rapport Therapeutics, Inc. RAPP 0001778071 Third Rock Ventures V, L.P. false C/O THIRD ROCK VENTURES, LLC 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 false false true false 0001977498 Third Rock Ventures GP V, LP false 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 false false true false 0001990717 TRV GP V, LLC false 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 false false true false 0001931056 Third Rock Ventures VI, L.P. false C/O THIRD ROCK VENTURES, LLC 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 false false true false 0001977499 Third Rock Ventures GP VI, L.P. false 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 false false true false 0001990716 TRV GP VI, LLC false 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 false false true false true Common Stock 2026-05-07 4 S false 271495 40.121 D 6437733 D Common Stock 2026-05-08 4 S false 5018 40.306 D 6432715 D Common Stock 969218 I By Third Rock Ventures VI, L.P. The reported transactions were effected pursuant to a Rule 10b5-1 trading plan dated November 21, 2025, previously adopted by the Reporting Person. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.00 to $40.60, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2). These shares are directly held by Third Rock Ventures V, L.P. ("TRV V"). The general partner of TRV V is Third Rock Ventures GP V, L.P. ("TRV GP V"). The general partner of TRV GP V is TRV GP V, LLC ("TRV GP V LLC"). Each of TRV GP V and TRV GP V LLC disclaims beneficial ownership of the shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.10 to $40.80, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4). The shares are held directly by Third Rock Ventures VI, L.P. ("TRV VI"). The general partner of TRV VI is Third Rock Ventures GP VI, L.P. ("TRV GP VI"). The general partner of TRV GP VI is TRV GP VI, LLC ("TRV GP VI LLC"). Each of TRV GP VI, and TRV GP VI LLC, disclaims beneficial ownership of these shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares. Each of Reporting Persons disclaims the existence of a Section 13(d) "group" as between any TRV V related parties and any TRV VI related parties and this report shall not be deemed an admission that any of such parties is or may be part of such a group with any of the other parties. /s/ Kevin Gillis, Chief Operating Officer of TRV GP V, LLC, general partner of Third Rock Ventures GP V, L.P., general partner of Third Rock Ventures V, L.P. 2026-05-11 /s/ Kevin Gillis, Chief Operating Officer of TRV GP V, LLC, general partner of Third Rock Ventures GP V, L.P. 2026-05-11 /s/ Kevin Gillis, Chief Operating Officer of TRV GP V, LLC 2026-05-11