X0306 4 2017-04-17 0 0001212458 PROOFPOINT INC PFPT 0001527210 Newell Tracey C/O PROOFPOINT, INC. 892 ROSS DRIVE SUNNYVALE CA 94089 0 1 0 0 EVP, Worldwide Sales Common Stock 2017-04-17 4 S 0 8183 75.2786 D 18346 D The transactions reported on this Form 4 were effected pursuant to a 10b5-1 trading plan adopted by the reporting person on March 9, 2017. 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 $74.66 to $75.59 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. /s/ Tracey Newell by Michael Yang, Attorney-in-Fact 2017-04-19