X0306 4 2018-03-01 0 0001501989 CytomX Therapeutics, Inc. CTMX 0001706863 RAY DEBANJAN C/O CYTOMX THERAPEUTICS, INC. 151 OYSTER POINT BLVD., SUITE 400 SOUTH SAN FRANCISCO CA 94080 0 1 0 0 Chief Financial Officer Common Stock 2018-03-01 4 M 0 13000 1.2599 A 17741 D Common Stock 2018-03-01 4 S 0 13000 29.4032 D 4741 D Common Stock 2018-03-02 4 M 0 5515 1.2599 A 10256 D Common Stock 2018-03-02 4 S 0 5515 30.059 D 4741 D Common Stock 2018-03-02 4 M 0 14485 1.1339 A 19226 D Common Stock 2018-03-02 4 S 0 12541 30.411 D 6685 D Common Stock 2018-03-02 4 S 0 1944 31.015 D 4741 D Stock Option (Right to Buy) 1.2599 2018-03-01 4 M 0 13000 0.00 D 2023-12-10 Common Stock 13000 20225 D Stock Option (Right to Buy) 1.2599 2018-03-02 4 M 0 5515 0.00 D 2023-12-10 Common Stock 5515 14710 D Stock Option (Right to Buy) 1.1339 2018-03-02 4 M 0 14485 0.00 D 2021-09-13 Common Stock 14485 20000 D The sale was effected pursuant to the Reporting Person's Rule 10b5-1 trading plan. The price reported in Column 4 is a weighted average sale price. These shares were sold in multiple transactions at prices ranging from $29.00 to $29.81, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price. These shares were sold in multiple transactions at prices ranging from $30.00 to $30.38, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price. These shares were sold in multiple transactions at prices ranging from $30.00 to $30.99, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price. These shares were sold in multiple transactions at prices ranging from $31.00 to $31.09, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. 100% of the shares subject to the option are fully vested and exercisable. /s/ Debanjan Ray 2018-03-05