SEC FORM 3 SEC Form 3
FORM 3 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number: 3235-0104
Estimated average burden
hours per response: 0.5
1. Name and Address of Reporting Person*
Mandal Sumant

(Last) (First) (Middle)
C/O THE RUBICON PROJECT, INC.
12181 BLUFF CREEK DRIVE, 4TH FLOOR

(Street)
LOS ANGELES CA 90094

(City) (State) (Zip)
2. Date of Event Requiring Statement (Month/Day/Year)
04/01/2014
3. Issuer Name and Ticker or Trading Symbol
RUBICON PROJECT, INC. [ RUBI ]
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
X Director X 10% Owner
Officer (give title below) Other (specify below)
5. If Amendment, Date of 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
Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)
Class A Common Stock(1) 324,237 I See Footnote(2)
Class A Common Stock(1) 5,796 I See Footnote(3)
Table II - Derivative Securities Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4) 2. Date Exercisable and Expiration Date (Month/Day/Year) 3. Title and Amount of Securities Underlying Derivative Security (Instr. 4) 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 6. Nature of Indirect Beneficial Ownership (Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Series A Convertible Preferred Stock (4) (4) Class A Common Stock(1) 3,022,962 (4) I See Footnote(2)
Series A Convertible Preferred Stock (4) (4) Class A Common Stock(1) 54,038 (4) I See Footnote(3)
Series B Convertible Preferred Stock (4) (4) Class A Common Stock(1) 1,946,205 (4) I See Footnote(2)
Series B Convertible Preferred Stock (4) (4) Class A Common Stock(1) 34,790 (4) I See Footnote(3)
Series C Convertible Preferred Stock (4) (4) Class A Common Stock(1) 348,781 (4) I See Footnote(2)
Series C Convertible Preferred Stock (4) (4) Class A Common Stock(1) 6,235 (4) I See Footnote(3)
Series D Convertible Preferred Stock (4) (4) Class A Common Stock(1) 547,155 (4) I See Footnote(2)
Series D Convertible Preferred Stock (4) (4) Class A Common Stock(1) 9,781 (4) I See Footnote(3)
Explanation of Responses:
1. Pursuant to the Sixth Amended and Restated Certificate of Incorporation (the "A&R Charter") of The Rubicon Project, Inc. (the "Issuer") to be filed immediately prior to the completion of the Issuer's initial public offering, effective upon the filing of the A&R Charter each share of Class A Common Stock (including each share of Class A Common Stock issued upon the conversion of shares of the Company's Convertible Preferred Stock upon closing of the Issuer's initial public offering) will be automatically reclassified and converted into one share of a single class of Common Stock.
2. These shares are held by Clearstone Venture Partners III-A, LP ("CVP-A"). The reporting person is a managing member of Clearstone Venture Management III, LLC, which is the general partner of CVP-A. The reporting person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of the reported shares for purposes of Section 16 or for any other purpose.
3. These shares are held by Clearstone Venture Partners III-B, a Delaware Multiple Series LLC ("CVP-B"). The reporting person is a managing member of Clearstone Venture Management III, LLC, which is the managing member of CVP-B. The reporting person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of the reported shares for purposes of Section 16 or for any other purpose.
4. Each share of Convertible Preferred Stock will automatically convert into 1/2 of a share of Class A Common Stock upon completion of the Issuer's initial public offering of its Common Stock. The Convertible Preferred Stock has no expiration date.
Remarks:
Exhibit 24.1 - Power of Attorney.
/s/ Jonathan Feldman, attorney-in-fact 04/01/2014
** Signature of Reporting Person Date
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 5 (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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
EXHIBIT 24

                                POWER OF ATTORNEY

                  FOR SEC FILINGS ON FORMS ID, 3, 4, 5 AND 144
                           IN RESPECT OF SECURITIES OF
                            THE RUBICON PROJECT, INC.

               The undersigned hereby constitutes and appoints Todd Tappin,
Brian Copple, David Day and Jonathan Feldman, and each of them, as his true and
lawful attorney-in-fact and agent, with full power of substitution and
resubstitution for him in his name and stead in any and all capacities, to sign
and file for and on his behalf, in respect of any acquisition, disposition or
other change in ownership of any Common Stock of The Rubicon Project, Inc. (the
"Company"), the following:

       (i)     any Form ID to be filed with the Securities and Exchange
               Commission (the "SEC");

       (ii)    any Initial Statement of Beneficial Ownership of Securities on
               Form 3 to be filed with the SEC;

       (iii)   any Statement of Changes of Beneficial Ownership of Securities
               on Form 4 to be filed with the SEC;

       (iv)    any Annual Statement of Beneficial Ownership of Securities on
               Form 5 to be filed with the SEC;

       (v)     any Notice of Proposed Sale of Securities on Form 144 to be filed
               with the SEC; and

       (vi)    any and all agreements, certificates, receipts, or other
               documents in connection therewith.

               The undersigned hereby gives full power and authority to the
attorney-in-fact to seek and
 obtain as the undersigned's representative and on
the undersigned's behalf, information on transactions in the Company's
securities from any third party, including brokers, employee benefit plan
administrators and trustees, and the undersigned hereby authorizes any such
person to release such information to the undersigned and approves and ratifies
any such release of information.

               The undersigned hereby grants unto such attorney-in-fact and
agent full power and authority to do and perform each and every act and thing
requisite and necessary in connection with such matters and hereby ratifies and
confirms all that any such attorney-in-fact and agent or substitute may do or
cause to be done by virtue hereof.

               The undersigned acknowledges that:

       (i)     neither the Company nor such attorney-in-fact assumes (i) any
               liability for the undersigned's responsibility to comply with the
               requirement of the Securities Exchange Act of 1934, as amended
               (the "Exchange Act"), (ii) any liability of the undersigned for
               any failure to comply with such requirements or (iii) any
               obligation or liability of the undersigned for profit
               disgorgement under Section 16(b) of the Exchange Act; and

       (ii)    this Power of Attorney does not relieve the undersigned from
               responsibility for compliance with the undersigned's obligations
               under the Exchange Act, including without limitation the
               reporting requirements under Section 16 of the Exchange Act.

               This Power of Attorney shall remain in full force and effect
until revoked by the undersigned in a signed writing delivered to such
attorney-in-fact.

               IN WITNESS WHEREOF, the undersigned has executed this Power of
Attorney.

Date:  March 18, 2014                   /s/ Sumant Mandal
                                        ----------------------------------------
                                        Sumant Mandal
                                        Director