X0305 4 2012-05-23 0 0001212458 PROOFPOINT INC PFPT 0001129541 MDV VII LP 3000 SAND HILL ROAD, BLDG. 3, SUITE 290 MENLO PARK CA 94025 1 0 1 0 0001027621 FEIBER JONATHAN D 3000 SAND HILL ROAD 3-290 MENLO PARK CA 94025 1 0 0 0 0001250354 SCHOENDORF NANCY J 3000 SAND HILL ROAD, 3-290 MENLO PARK CA 94025 1 0 1 0 Common Stock 2012-05-23 4 S 0 49458 13.00 D 4047334 D Shares sold as part of the exercise of the underwriters' over-allotment option in connection with the Issuer's initial public offering. Shares directly held by MDV VII, L.P. ("MDV"). Jonathan Feiber, a director of the Issuer, and Nancy J. Schoendorf are managing members of Seventh MDV Partners, L.L.C., the general partner of MDV, and may be deemed to share voting and dispositive power over the shares held by MDV. Mr. Feiber and Ms. Schoendorf disclaim beneficial ownership of the shares held by MDV except to the extent of any pecuniary interest therein. /s/ Jonathan Feiber, as a managing member of Seventh MDV Partners, L.L.C., the general partner of MDV VII, L.P. 2012-05-23 /s/ Jonathan Feiber 2012-05-23 /s/ Nancy J. Schoendorf 2012-05-23