LOCK-UP AGREEMENT

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.23

LOCK-UP AGREEMENT

         THIS LOCK-UP AGREEMENT (this "Lock-Up Agreement"), dated as of                          , 2009, by and among Prospect Acquisition Corp., a Delaware corporation (the "Company") and                                      (the "Stockholder").

         WHEREAS , the Company was organized to serve as a vehicle to effect a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or other similar business combination with one or more operating business in the financial services industry ("Business Combination");

         WHEREAS , the Company consummated an initial public offering in November 2007 ("IPO") in connection with which it raised net proceeds of approximately $247.0 million which were placed in a trust account pending the consummation of a Business Combination, or the dissolution and liquidation of the Company, in the event it is unable to consummate a Business Combination by November 14, 2009;

         WHEREAS , the Company expects to consummate a Business Combination with Kennedy-Wilson, Inc. (the "Acquisition") pursuant to certain agreements.

         WHEREAS, the Stockholder owns                      shares of the Company's common stock, of which the Company desires that                      shares ⁽¹⁾ (the "Three Month Shares") be locked up for three months and that                      shares ⁽²⁾ (the "One-Year Shares") be locked up for one year, and which the Stockholder has agreed that it will lock-up for such periods of time.

        (1)   10% of shares received as merger consideration.

        (2)   90% of shares received as merger consideration and 100% of Management Incentive Shares.

         NOW, THEREFORE, for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties hereto agree that, subject to consummation of the Business Combination:

        Section 1.     (a)    The Stockholder may not offer, sell, contract to sell, pledge or grant any option to purchase or otherwise dispose of or offer to dispose of (collectively, a "Disposition") any of the Three-Month Shares for a period commencing on the date hereof and ending on                          , 2010, inclusive, or any of the One-Year Shares for a period commencing on the date hereof and ending on                          , 2010, inclusive, without the prior written consent of the Company; provided, however, that the Stockholder may transfer any Shares: (1) to any partner, shareholder or member of the Stockholder if, prior to such transfer, such partner, shareholder or member agrees in writing to be bound by the restrictions set forth herein; (2) to any controlled affiliate of the Stockholder if, prior to such transfer, such affiliate agrees in writing to be bound by the restrictions set forth herein, or (3) for estate planning purposes if, prior to such transfer, the person receiving such Shares agrees in writing to be bound by the restrictions set forth herein.

        (b)   For the purpose of effectuating this Lock-Up Agre