ASSUMPTION AND JOINDER AGREEMENT TO SECURITY AND PLEDGE AGREEMENT

EXHIBIT 10.3

ASSUMPTION AND JOINDER AGREEMENT TO

SECURITY AND PLEDGE AGREEMENT

With reference to that certain Amended and Restated Security and Pledge Agreement dated September 26, 2007 (the “Security Agreement”; capitalized terms used herein without definition have the meanings given in the Security Agreement) by and among ARCO CAPITAL CORPORATION LTD. on (“ACC”) on the one hand and LUMINENT MORTGAGE CAPITAL, INC. (“Luminent”) and the Subsidiary Guarantors, on the other hand:

WHEREAS, Luminent as “Borrower” under that certain Amended and Restated Credit Agreement dated September 26, 2007 (as amended by that certain First Amendment to Amended and Restated Credit Agreement dated as of December 7, 2007 as the same may be further amended, supplemented or otherwise modified from time to time, the “Credit Agreement”), and the members of the Luminent Group named therein as “Guarantors”, have requested that ACC as “Lender” thereunder enter into a second amendment to the Credit Agreement (the “Second Amendment”); and

WHEREAS, OT REALTY TRUST (the “New Subsidiary Guarantor”) understands that execution of this Assumption and Joinder Agreement is a condition precedent to the execution of the Second Amendment;

NOW, THEREFORE, as an inducement to ACC to enter into that Second Amendment, the New Subsidiary Guarantor agrees to join in the Security Agreement and agrees to be bound by all of the terms and provisions thereof as a Subsidiary Guarantor.

IN WITNESS WHEREOF, the undersigned has executed this Agreement this 9th day of May, 2008.

OT REALTY TRUST, as the New Guarantor

Title: SVP, Secretary and Treasurer