X0306 4 2016-01-22 0 0001212458 PROOFPOINT INC PFPT 0001547394 Knight David C/O PROOFPOINT, INC. 892 ROSS DRIVE SUNNYVALE CA 94089 0 1 0 0 EVP&GM, Info Security Products Common Stock 2016-01-22 4 M 0 3700 7.98 A 5261 D Common Stock 2016-01-22 4 S 0 3700 60.02 D 1561 D Non-qualified stock option (right to buy) 7.98 2016-01-22 4 M 0 1561 0 D 2022-01-23 Common Stock 1561 0 D Incentive stock option (right to buy) 7.98 2016-01-22 4 M 0 2139 0 D 2022-01-23 Common Stock 2139 10300 D The transactions reported on this Form 4 were effected pursuant to a 10b5-1 trading plan adopted by the reporting person on August 6, 2014. 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 $60.00 to $60.19 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. The stock option is immediately exercisable in full. /s/ David Knight By Michael Yang, Attorney-In-Fact 2016-01-25