Sec Form 4 Filing - Meritech Management Associates II L.L.C. @ PROOFPOINT INC - 2013-04-29

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Meritech Management Associates II L.L.C. 2. Issuer Name and Ticker or Trading Symbol PROOFPOINT INC [ PFPT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 245 LYTTON AVENUE, SUITE 350, 3. Date of Earliest Transaction (MM/DD/YY) 04/29/2013 (Street) PALO ALTO, CA94301 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 04/29/2013 S 96,770 D $ 18.6 ( 1 ) 2,923,962 I See footnote ( 2 ) Common Stock 04/29/2013 S 2,490 D $ 18.6 ( 1 ) 75,236 I See footnote ( 3 ) Common Stock 04/29/2013 S 740 D $ 18.6 ( 1 ) 22,359 I See footnote ( 4 ) Common Stock 04/30/2013 S 3,924 D $ 18.5 2,920,038 I See footnote ( 2 ) Common Stock 04/30/2013 S 101 D $ 18.5 75,135 I See footnote ( 3 ) Common Stock 04/30/2013 S 30 D $ 18.5 22,329 I See footnote ( 4 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Meritech Management Associates II L.L.C. 245 LYTTON AVENUE, SUITE 350 PALO ALTO, CA94301 X Meritech Capital Associates II L.L.C. 245 LYTTON AVENUE, SUITE 350 SUITE 200 PALO ALTO, CA94301 X MERITECH CAPITAL PARTNERS II LP 245 LYTTON AVENUE, SUITE 350 SUITE 200 PALO ALTO, CA94301 X MERITECH CAPITAL AFFILIATES II LP 245 LYTTON AVENUE, SUITE 350 SUITE 200 PALO ALTO, CA94301 X MCP ENTREPRENEUR PARTNERS II LP 245 LYTTON AVENUE, SUITE 350 SUITE 200 PALO ALTO, CA94301 X MADERA PAUL S 245 LYTTON AVENUE, SUITE 350 PALO ALTO, CA94301 X GORDON MICHAEL B 245 LYTTON AVENUE, SUITE 350 PALO ALTO, CA94301 X Signatures /s/ Joel Backman, by power of attorney for Meritech Management Associates II L.L.C. 05/01/2013 Signature of Reporting Person Date /s/ Joel Backman, by power of attorney for Meritech Management Associates II L.L.C., the managing member of Meritech Capital Associates II L.L.C. 05/01/2013 Signature of Reporting Person Date /s/ Joel Backman, by power of attorney for Meritech Management Associates II L.L.C., the managing member of Meritech Capital Associates II L.L.C., the general partner of Meritech Capital Partners II L.P. 05/01/2013 Signature of Reporting Person Date /s/ Joel Backman, by power of attorney for Meritech Management Associates II L.L.C., the managing member of Meritech Capital Associates II L.L.C., the general partner of Meritech Capital Affiliates II L.P. 05/01/2013 Signature of Reporting Person Date /s/ Joel Backman, by power of attorney for Meritech Management Associates II L.L.C., the managing member of Meritech Capital Associates II L.L.C., the general partner of MCP Entrepreneur Partners II L.P. 05/01/2013 Signature of Reporting Person Date /s/ Joel Backman, by power of attorney for Paul S. Madera 05/01/2013 Signature of Reporting Person Date /s/ Joel Backman, by power of attorney for Michael B. Gordon 05/01/2013 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $18.50 to $19.04, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote 1 to this Form 4. ( 2 )The reported securities are held of record by Meritech Capital Partners II L.P. ("MCP II"). Meritech Capital Associates II L.L.C., the general partner of MCP II, has sole voting and dispositive power with respect to the securities held by MCP II. The managing member of Meritech Capital Associates II L.L.C. is Meritech Management Associates II L.L.C. Paul S. Madera and Michael B. Gordon, the managing members of Meritech Management Associates II L.L.C., share voting and dispositive power with respect to the shares held by MCP II. Such persons and entities disclaim beneficial ownership of the securities held by MCP II except to the extent of any pecuniary interest therein. ( 3 )The reported securities are held of record by Meritech Capital Affiliates II L.P ("MCA II"). Meritech Capital Associates II L.L.C., the general partner of MCA II, has sole voting and dispositive power with respect to the securities held by MCA II. The managing member of Meritech Capital Associates II L.L.C. is Meritech Management Associates II L.L.C. Paul S. Madera and Michael B. Gordon, the managing members of Meritech Management Associates II L.L.C., share voting and dispositive power with respect to the shares held by MCA II. Such persons and entities disclaim beneficial ownership of the securities held by MCA II except to the extent of any pecuniary interest therein. ( 4 )The reported securities are held of record by MCP Entrepreneur Partners II L.P ("MCPEP II"). Meritech Capital Associates II L.L.C., the general partner of MCPEP II, has sole voting and dispositive power with respect to the securities held by MCPEP II. The managing member of Meritech Capital Associates II L.L.C. is Meritech Management Associates II L.L.C. Paul S. Madera and Michael B. Gordon, the managing members of Meritech Management Associates II L.L.C., share voting and dispositive power with respect to the shares held by MCPEP II. Such persons and entities disclaim beneficial ownership of the securities held by MCPEP II except to the extent of any pecuniary interest therein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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