Sec Form 4 Filing - TAPPIN TODD L @ RUBICON PROJECT, INC. - 2016-05-25

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 TAPPIN TODD L 2. Issuer Name and Ticker or Trading Symbol RUBICON PROJECT, INC. [ RUBI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) CFO & COO (Last) (First) (Middle) C/O THE RUBICON PROJECT, INC., 12181 BLUFF CREEK DRIVE, 4TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 05/25/2016 (Street) LOS ANGELES, CA90094 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 441,327 D

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 Stock Option (right to buy) $ 7.8 ( 1 ) 02/01/2023 Common Stock 111,302 111,302 D Stock Option (right to buy) $ 16.75 ( 2 ) 05/19/2025 Common Stock 59,864 59,864 D Stock Option (right to buy) $ 13.16 ( 3 ) 02/01/2026 Common Stock 56,286 56,286 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other TAPPIN TODD L C/O THE RUBICON PROJECT, INC. 12181 BLUFF CREEK DRIVE, 4TH FLOOR LOS ANGELES, CA90094 CFO & COO Signatures /s/ Jonathan Feldman, attorney-in-fact 05/26/2016 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The option, representing a right to purchase a total of 593,650 shares, became exercisable with respect to 25% of the grant on January 28, 2014 and becomes exercisable with respect to the remainder in 36 equal installments each calendar month thereafter until cessation of continuous service. ( 2 )25% of the stock options will vest on February 1, 2016 and the remaining option shares will become exercisable in 36 equal installments each calendar month thereafter until cessation of continuous service. ( 3 )25% of the stock options will vest on February 1, 2017 and the remaining option shares will become exercisable in 36 equal installments each calendar month thereafter until cessation of continuous service.

Remarks: The reporting person resigned as The Rubicon Project, Inc.'s Chief Financial Officer and Chief Operating Officer effective May 25, 2016. As a result, the reporting person is no longer subject to Section 16 in connection with his transactions in the equity securities of The Rubicon Project, Inc. and therefore will no longer report any such transactions on Form 4 or Form 5.

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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