Ownership Submission
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 OF SECURITIES

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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(Print or Type Responses)
1. Name and Address of Reporting Person *
MOHN JARL
  2. Issuer Name and Ticker or Trading Symbol
RUBICON PROJECT, INC. [RUBI]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
C/O THE RUBICON PROJECT, INC., 12181 BLUFF CREEK DRIVE, 4TH FLOOR
3. Date of Earliest Transaction (Month/Day/Year)
04/01/2014
(Street)

LOS ANGELES, CA 90094
4. If Amendment, Date Original Filed(Month/Day/Year)
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 (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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
Class A Common Stock 04/01/2014   A   15,000 (1) A $ 0 (2) 15,000 D  
Class A Common Stock 04/01/2014   A   6,283 (3) A $ 0 (2) 21,283 D  
Class A Common Stock 04/07/2014   J(4)   21,283 D (4) 0 D  
Common Stock 04/07/2014   J(4)   21,283 A (4) 21,283 D  
Class A Common Stock 04/07/2014   C(5)   405,850 A (5) 405,850 I By The Mohn Family Trust (6)
Class A Common Stock 04/07/2014   J(4)   405,850 D (4) 0 I By The Mohn Family Trust (6)
Common Stock 04/07/2014   J(4)   405,850 A (4) 405,850 I By The Mohn Family Trust (6)
Common Stock 04/07/2014   S   50,000 D $ 15 355,850 I By The Mohn Family Trust (6)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 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
(Month/Day/Year)
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) $ 15 04/01/2014   A   29,184     (7) 04/01/2024 Class A Common Stock 29,184 $ 0 (2) 29,184 D  
Stock Option (Right to Buy) $ 15 04/01/2014   A   13,208     (8) 04/01/2024 Class A Common Stock 13,208 $ 0 (2) 13,208 D  
Stock Option (Right to Buy) $ 15 04/07/2014   J(9)     29,184   (7) 04/01/2024 Class A Common Stock 29,184 (9) 0 D  
Stock Option (Right to Buy) $ 15 04/07/2014   J(9)   29,184     (7) 04/01/2024 Common Stock 29,184 (9) 29,184 D  
Stock Option (Right to Buy) $ 15 04/07/2014   J(9)     13,208   (8) 04/01/2024 Class A Common Stock 13,208 (9) 0 D  
Stock Option (Right to Buy) $ 15 04/07/2014   J(9)   13,208     (8) 04/01/2024 Common Stock 13,208 (9) 13,208 D  
Series B Convertible Preferred Stock (5) 04/07/2014   C(5)     705,880   (5)   (5) Class A Common Stock 352,940 (5) (5) 0 I By The Mohn Family Trust (6)
Series C Convertible Preferred Stock (5) 04/07/2014   C(5)     49,544   (5)   (5) Class A Common Stock 24,772 (5) (5) 0 I By The Mohn Family Trust (6)
Series D Convertible Preferred Stock (5) 04/07/2014   C(5)     56,276   (5)   (5) Class A Common Stock 28,138 (5) (5) 0 I By The Mohn Family Trust (6)

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
MOHN JARL
C/O THE RUBICON PROJECT, INC.
12181 BLUFF CREEK DRIVE, 4TH FLOOR
LOS ANGELES, CA 90094
  X      

Signatures

 /s/ Jonathan Feldman, attorney-in-fact   04/11/2014
**Signature of Reporting Person Date

Explanation of Responses:

* 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).
(1) Represents restricted stock units that vest in three equal annual increments, on the first, second and third anniversaries of the date of completion of The Rubicon Project, Inc.'s (the "Issuer") initial public offering.
(2) Granted as compensation for services.
(3) Represents restricted stock units that vest in full on the date of the next Annual Meeting of the Issuer's stockholders.
(4) Pursuant to the Sixth Amended and Restated Certificate of Incorporation ("A&R Charter") of the Issuer filed prior to the completion of the Issuer's initial public offering, each share of Class A Common Stock was reclassified and converted into one share of a single class of Common Stock on April 7, 2014. Such reclassification was exempt under Rule 16b-7 of the Securities Exchange Act of 1934, as amended.
(5) Each share of Convertible Preferred Stock automatically converted into 1/2 of a share of Class A Common Stock upon completion of the Issuer's initial public offering of its Common Stock on April 7, 2014. The Convertible Preferred Stock has no expiration date.
(6) Mr. Mohn and his wife are co-trustees of, and the sole beneficiaries of, The Mohn Family Trust.
(7) The stock option vests in three equal annual increments, on the first, second and third anniversaries of the date of completion of the Issuer's initial public offering.
(8) The stock option vests in full on the date of the next Annual Meeting of the Issuer's stockholders.
(9) Pursuant to the A&R Charter, each share of Class A Common Stock underlying the reported stock option automatically reclassified and converted into one share of a single class of Common Stock on April 7, 2014, immediately prior to the completion of the Issuer's initial public offering. Such reclassification was exempt under Rule 16b-7 of the Securities Exchange Act of 1934, as amended.

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