X0306 4 2017-02-01 0 0001640455 Jounce Therapeutics, Inc. JNCE 0001591092 Pfeffer Cary C/O THIRD ROCK VENTURES, LLC, 29 NEWBURY STREET, 3RD FLOOR BOSTON MA 02116 1 0 0 0 Common Stock 2017-02-01 4 C 0 0 A 0 I See Footnote Common Stock 2017-02-01 4 C 0 0 A 0 I See Footnote Series A Preferred Stock 2017-02-01 4 C 0 0 0.00 D Common Stock 0 0 I See Footnote Series A Preferred Stock 2017-02-01 4 C 0 0 0.00 D Common Stock 0 0 I See Footnote Third Rock Ventures II, L.P. ("TRV II") received 9,688,344 shares of Common Stock upon conversion of Series A Preferred Stock in connection with the closing of the Issuer's initial public offering. Third Rock Ventures III, L.P. ("TRV III") received 3,048,780 shares of Common Stock upon conversion of Series A Preferred Stock in connection with the closing of the Issuer's initial public offering. Each share of Series A Preferred Stock converted into Common Stock on a one-for-3.69 basis upon the closing of the Issuer's initial public offering without payment or consideration. Each share of Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The Series A Preferred Stock had no expiration date. TRV II and TRV III converted 35,750,000 and 11,250,000 shares of Series A Preferred Stock into Common Stock, respectively, upon the closing of the Issuer's initial public offering. TRV II directly holds 10,230,349 shares of Common Stock. The reporting person is a partner of Third Rock Ventures GP II, L.P., which is the general partner of the TRV II. The reporting person disclaims beneficial ownership over such shares, except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that he is the beneficial owner of such shares. TRV III directly holds 3,048,780 shares of Common Stock. The reporting person is a partner of Third Rock Ventures GP III, L.P., which is the general partner of the TRV III. The reporting person disclaims beneficial ownership over such shares, except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that he is the beneficial owner of such shares. /s/ Cary Pfeffer 2017-02-03