X0306 4 2016-09-28 0 0001212458 PROOFPOINT INC PFPT 0001547393 Hahn Eric C/O PROOFPOINT, INC. 892 ROSS DRIVE SUNNYVALE CA 94089 1 0 0 1 Chairman Common Stock 2016-09-28 4 M 0 5000 2.30 A 121215 D Common Stock 2016-09-28 4 S 0 4600 77.7423 D 116615 D Common Stock 2016-09-28 4 S 0 400 78.73 D 116215 D Common Stock 213718 I By Family Trust Non-qualified stock option (right to buy) 2.3 2016-09-28 4 M 0 5000 0 D 2017-07-18 Common Stock 5000 27835 D These transactions were effected pursuant to a 10b5-1 trading plan adopted by the reporting person on December 9, 2015. Represents the aggregate of sales effected on the same day at different prices. Represents the weighted average sales price per share. The shares sold at prices ranging from $77.44 to $78.73 per share. Full information regarding the number of shares sold at each price shall be provided upon request to the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer. Shares directly held by the Hahn Family Trust dated 10/20/1999, of which the Reporting Person is a trustee and may be deemed to share voting and dispositive power over these shares. The stock option is immediately exercisable in full. /s/ Eric Hahn By Michael Yang, Attorney-In-Fact 2016-09-30