X0306 4 2019-02-12 0 0001708493 Harpoon Therapeutics, Inc. HARP 0001609492 MPM BioVentures 2014, L.P. C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001263048 MPM ASSET MANAGEMENT LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001609493 MPM BioVentures 2014 (B), L.P. C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001609495 MPM Asset Management Investors BV2014 LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001765021 MPM BioVentures 2014 LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001765091 MPM BioVentures 2014 GP LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001473930 Foley Todd C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 Common Stock 2019-02-12 4 C 0 1525164 A 1847227 I See Footnote Common Stock 2019-02-12 4 C 0 1578751 A 3425978 I See Footnote Common Stock 2019-02-12 4 C 0 417852 A 3843830 I See Footnote Common Stock 2019-02-12 4 X 0 432119 0.0492 A 4275949 I See Footnote Common Stock 2019-02-12 4 S 0 1524 14.00 D 4274425 I See Footnote Common Stock 2019-02-12 4 P 0 250000 14.00 A 4524425 I See Footnote Series A Preferred Stock 2019-02-12 4 C 0 1525164 0.00 D Common Stock 1525164 0 I See Footnote Series B Preferred Stock 2019-02-12 4 C 0 1578751 0.00 D Common Stock 1578751 0 I See Footnote Series C Preferred Stock 2019-02-12 4 C 0 417852 0.00 D Common Stock 417852 0 I See Footnote Common Stock Warrant (Right to Buy) 0.0492 2019-02-12 4 X 0 25418 0.00 D 2015-03-24 2025-03-24 Common Stock 25418 0 I See Footnote Common Stock Warrant (Right to Buy) 0.0492 2019-02-12 4 X 0 57192 0.00 D 2015-07-23 2025-07-23 Common Stock 57192 0 I See Footnote Common Stock Warrant (Right to Buy) 0.0492 2019-02-12 4 X 0 171579 0.00 D 2015-08-19 2025-08-19 Common Stock 171579 0 I See Footnote Common Stock Warrant (Right to Buy) 0.0492 2019-02-12 4 X 0 50837 0.00 D 2015-12-16 2025-12-16 Common Stock 50837 0 I See Footnote Common Stock Warrant (Right to Buy) 0.0492 2019-02-12 4 X 0 76256 0.00 D 2016-11-01 2026-11-01 Common Stock 76256 0 I See Footnote Common Stock Warrant (Right to Buy) 0.0492 2019-02-12 4 X 0 50837 0.00 D 2017-01-10 2027-01-10 Common Stock 50837 0 I See Footnote All series of convertible preferred stock automatically converted into the number of shares of the Issuer's common stock on a 1-for-1 basis, for no additional consideration, immediately prior to the closing of the Issuer's initial public offering and had no expiration date. The shares are held as follows: 1,382,777 by MPM BioVentures 2014, L.P. ("BV 2014"), 92,229 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 50,158 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 322,063 by MPM Asset Management LLC ("AM LLC"). MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). Luke Evnin, Ansbert Gadicke and Todd Foley are the members of BV LLC and Luke Evnin and Anbert Gadicke are the members of AM LLC. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein. The shares are held as follows: 2,814,142 by BV 2014, 187,696 by BV 2014(B), 102,077 by AM BV2014 and 322,063 by MPM LLC. The shares are held as follows: 3,192,985 by BV 2014, 212,964 by BV 2014(B), 115,818 by AM BV2014 and 322,063 by MPM LLC. On February 12, 2019, BV 2014, BV 2014(B) and AM BV2014 exercised warrants to purchase an aggregate of 432,119 shares of the Issuer's common stock for $0.0492 per share. The warrants were exercised as follows: 391,784 by BV 2014, 26,129 by BV 2014(B) and 14,206 by AM BV2014. The exercise price was paid on a cashless basis, resulting in the Issuer's withholding of an aggregate of 1,524 of the warrant shares to pay the exercise price and issuing to the respective Reporting Persons the remaining 430,595 shares. The shares are held as follows: 3,584,769 by BV 2014, 239,093 by BV 2014(B), 130,024 by AM BV2014 and 322,063 by MPM LLC. The shares are held as follows: 3,583,391 by BV 2014, 238,998 by BV 2014(B), 129,973 by AM BV2014 and 322,063 by MPM LLC. The shares are held as follows: 3,810,051 by BV 2014, 254,116 by BV 2014(B), 138,195 by AM BV2014 and 322,063 by MPM LLC. No securities held by the Reporting Persons. /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC, the general partner of MPM BioVentures 2014, L.P. 2019-02-14 /s/ Ansbert Gadicke, managing member of MPM Asset Management 2019-02-14 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC, the general partner of MPM BioVentures 2014 (B), L.P. 2019-02-14 /s/ Howard Rubin, director of MPM Asset Management Investors BV2014 LLC 2019-02-14 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC 2019-02-14 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC 2019-02-14 /s/ Todd Foley 2019-02-14