X0306 4 2019-09-06 0 0001478121 Pfenex Inc. PFNX 0001612843 Lucy Patrick K. C/O PFENEX INC., 10790 ROSELLE STREET SAN DIEGO CA 92121 0 1 0 0 Chief Business Officer Common Stock 2019-09-06 4 S 0 6000 8.0035 D 98622 D The sale of shares reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan entered into by the reporting person on August 23, 2018. Represents the weighted average share price of an aggregate total of 6,000 shares sold in the price range of $8.00 to $8.05 by the reporting person. The reporting person undertakes to provide upon request by the Commission staff, the issuer or a security holder of the issuer, full information regarding the number of shares sold at each separate price. Includes 700 shares acquired under the PFNX 2014 employee stock purchase plan on February 15, 2017, 604 shares acquired under the PFNX 2014 employee stock purchase plan on August 15, 2018, 605 shares acquired under the PFNX 2014 employee stock purchase plan on February 15, 2019, and 623 shares acquired under the PFNX 2014 employee stock purchase plan on August 15, 2019. /s/ Patricia Lady, as Attorney-in-Fact 2019-09-09