UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.     )

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¨ Preliminary Proxy Statement

¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

¨ Definitive Proxy Statement

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¨ Soliciting Material Pursuant to §240.14a-12

THE RUBICON PROJECT, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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1. Election of two class i directors: frank addante robert j. frankenberg 2. approval of the material terms of the performance goals under the rubicon project, inc. 2015 executive cash incentive plan. 3. to ratify the selection of price water house coopers llp as the company’s independent registered public accounting firm for the current fiscal year. 4. to transact such other business as may properly come before the meeting or any postponements or adjournments thereof. the board of directors recommends a vote “for” the election of directors and “for” proposals 2 and 3. nominees: important notice of availability of proxy materials for the annual meeting of stockholders of to be held on: wednesday, may 13, 2015 at 12:00 p.m., pacific time at 12181 bluff creek drive, 4th floor, los angeles, california 90094 this communication presents only an overview of the more complete proxy materials that are available to you on the internet. we encourage you to access and review all of the important information contained in the proxy materials before voting. if you want to receive a paper or e-mail copy of the proxy materials you must request one. there is no charge to you for requesting a copy. to facilitate timely delivery please make the request as instructed below before may 1, 2015. please visit http://www.astproxyportal.com/ast/18899/, where the following materials are available for view: notice of annual meeting of stockholders proxy statement form of electronic proxy card annual report on form 10-k to request material: telephone: 888-proxy-na (888-776-9962) 718-921-8562 (for international callers) e-mail: info@amstock.com website: http://www.amstock.com/proxyservices/requestmaterials.asp to vote: online: to access your online proxy card, please visit www.voteproxy.com and follow the on-screen instructions or scan the qr code with your smartphone. you may enter your voting instructions at www.voteproxy.com up until 11:59 pm eastern time the day before the meeting date. in person: you may vote your shares in person by attending the annual meeting. telephone: to vote by telephone, please visit www.voteproxy.com to view the materials and to obtain the toll free number to call. mail: you may request a card by following the instructions above. company number account number control number john smith 1234 main street apt. 203 new york, ny 10038 please note that you cannot use this notice to vote by mail.