CytomX Therapeutics, Inc. — Director's Dealing 2016

May 23, 2016

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: CytomX Therapeutics, Inc. (CTMX)
CIK: 0001501989
Period of Report: 2016-05-19

Reporting Person: SHANNON TIMOTHY M (N/A)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2016-05-19	Common Stock	S	2500	$10.14	Disposed	4582255	Indirect
2016-05-20	Common Stock	S	6187	$10.09	Disposed	4576068	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	134	Direct

Footnotes

F1: These shares of Common Stock ("Shares") are held directly by Canaan IX L.P. The Reporting Person is a non-managing member of Canaan Partners IX LLC, the general partner of Canaan IX L.P. The Reporting Person does not have voting, investment or dispositive power over any of the Shares directly held by Canaan IX L.P. and disclaims beneficial ownership of the Shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of the Shares for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or for any other purpose.

F2: The price reported in Column 4 is a weighted average price. These Shares were sold in multiple transactions at prices ranging from $10.00 - $10.25, 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 range set forth in footnote (2) of this Form 4.

F3: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.00 - $10.20, 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 range set forth in footnote (3) of this Form 4.

F4: These shares of Common Stock were previously reported by the Reporting Person as indirectly beneficially owned. These shares became directly beneficially owned by the Reporting Person following pro rata distributions of shares on April 25, 2016 by Canaan IX L.P. and Canaan Partners IX LLC, which were exempt from Section 16 of the Exchange Act under Rule 16a-13.