THE FRANCIS G. NEWLANDS BUILDING ADDENDUM NO. 4 TO OFFICE LEASE

THIS ADDENDUM NO. 4 TO OFFICE LEASE (this “ Addendum No. 4 ”) is made and entered into this 2nd day of April, 2008, by and between NEWLANDS BUILDING VENTURE, LLC, a Maryland limited liability company, hereinafter called “ Lessor ”, and COSTAR REALTY INFORMATION, INC., a Delaware corporation, hereinafter called “ Lessee ”.

WHEREAS, by Office Lease dated August 12, 1999, as amended by Addendum No. 1 dated May 15, 2000 and Addendum No. 2 dated July 1, 2000, Lessor leased to Lessee approximately 60,041 square feet of rentable area (the “ Original Demised Premises ”) on the ninth (9 ^th ), tenth (10 ^th ) and eleventh (11 ^th ) floors of the office building situated at Two Bethesda Metro Center, Bethesda, Maryland (the “ Building ”), together with certain storage space therein;

WHEREAS, pursuant to Addendum No. 3 dated May 12, 2004 (the “ Addendum No. 3 ”), and said Office Lease as so amended by Addenda Nos. 1-3, collectively, the “ Lease ”), Lessor leased to Lessee additional space on the fourth (4 ^th ) floor of the Building comprising approximately 13,522 square feet of rentable area (the “ Additional Space ”); and

WHEREAS, Lessee desires to terminate the Lease with respect to the Additional Space, and Lessor is willing to agree to such early termination with respect to the Additional Space, on the terms and conditions set forth herein.

NOW, THEREFORE, in consideration of the mutual covenants and agreements hereinafter set forth, the parties hereto do mutually agree that the Lease shall be and is hereby amended to provide as follows, all capitalized terms being as defined in the Lease unless otherwise noted herein:

The term of the Lease with respect to the Additional Space is terminated effective as of 11:59 p.m. on April 27, 2008 (the “ Partial Termination Date ”), with the same force and effect as if such date were the expiration date under the Lease with respect to the Additional Space.  From and after the Partial Termination Date, the remaining premises leased by Lessee pursuant to the Lease shall be the Original Demised Premises, and all references in the Lease to “Demised Premises” shall mean and refer to the Original Demised Premises.  On or before 11:59 p.m. on the Partial Termination Date, Lessee shall surrender the Additional Space to Lessor free and clear of all occupancies and tenancies and in good order, repair and condition, broom clean and free of all personal property, furnishings and debris, and otherwise in accordance with the provisions of the Lease.  

Lessee has advised Lessor that it has made arrangements with the new tenant of the Additional Space, General Electric Capital Corporation (“ GECC ”), whereby Lessee would leave the existing furniture in t