¨

Preliminary Proxy Statement

¨

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

¨

Definitive Proxy Statement

þ

Definitive Additional Materials

¨

Soliciting Material Pursuant to §240.14a-12

Payment of Filing Fee (Check the appropriate box):

þ

No fee required.

¨

Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

(1)

Title of each class of securities to which transaction applies:

(2)

Aggregate number of securities to which transaction applies:

(3)

Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):

(4)

Proposed maximum aggregate value of transaction:

(5)

Total fee paid:

¨

Fee paid previously with preliminary materials.

¨

Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

(1)

Amount Previously Paid:

(2)

Form, Schedule or Registration Statement No.:

(3)

Filing Party:

(4)

Date Filed:

Meeting Information            

Meeting Type:

  Annual Meeting

PROS HOLDINGS, INC.

For holders as of:

  April 16, 2012

Date:    June 7, 2012

      Time: 8:00 a.m., CDT

Location:    Company Headquarters

   3100 Main Street

   Suite 900

   Houston, TX 77002

  PROS HOLDINGS, INC.

  3100 MAIN STREET

  SUITE 900

  HOUSTON, TX 77002

You are receiving this communication because you hold shares in the above named company.

This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side).

We encourage you to access and review all of the important information contained in the proxy materials before voting.

See the reverse side of this notice to obtain proxy materials and voting instructions.

Before You Vote  

Proxy Materials Available to VIEW or RECEIVE:

NOTICE AND PROXY STATEMENT        ANNUAL REPORT

How to View Online:

Have the information that is printed in the box marked by the arrow   (located on the following page) and visit: www.proxyvote.com.

How to Request and Receive a PAPER or E-MAIL Copy:

If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request:

                               1) BY INTERNET:         www.proxyvote.com

                               2) BY TELEPHONE:     1-800-579-1639

                               3) BY E-MAIL*:             sendmaterial@proxyvote.com

*  If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow (located on the following page) in the subject line.

Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before May 24, 2012 to facilitate timely delivery.

How To Vote  

Vote In Person: Many shareholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares.

Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow available and follow the instructions.

Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card.

The Board of Directors recommends that

you vote FOR the following:

1.     Election of Directors

        Nominees:

        01)    Ellen Keszler

        02)    William Russell

The Board of Directors recommends you vote FOR the following proposals:

2.    To ratify the appointment of PricewaterhouseCoopers LLP as the independent registered public accounting firm of

        PROS Holdings, Inc. for the fiscal year ending December 31, 2012.

3.    To approve, by non-binding advisory vote, the executive compensation as disclosed in the proxy statement.

NOTE: Such other business as may properly come before the meeting or any adjournment thereof will be voted at the proxies’ discretion.