Exhibit 10.27




THE
FRANCIS G. NEWLANDS BUILDING





ADDENDUM NO. 5 TO OFFICE
LEASE








THIS ADDENDUM NO. 5 TO OFFICE LEASE
(this “Addendum”) is made and entered into this 23rd day of October, 2009, by
and between (i) NEWLANDS BUILDING VENTURE, LLC, a Maryland limited liability
company (“Lessor”), and (ii) COSTAR REALTY INFORMATION, INC., a Delaware
corporation (“Lessee”).





WITNESSETH:





WHEREAS, by Office Lease dated August
12, 1999, as amended by (i) Addendum No. 1 to Office Lease dated May 15, 2000,
(ii) Addendum No. 2 to Office Lease dated as of July 1, 2000, (iii) Addendum No.
3 to Office Lease dated May 12, 2004, and (iv) Addendum No. 4 to Office Lease
April 2, 2008 (as so amended, the “Lease”), Lessor leased to Lessee
approximately 60,041 square feet of rentable area (the “Existing Demised
Premises”) on the ninth (9th), tenth (10th), and eleventh (11th) floors of the
office building situated at Two Bethesda Metro Center, Bethesda, Maryland (the
“Building”), together with certain storage space located on the P-2 level of the
Building (the “Storage Space”);





WHEREAS,
the term of the Lease expires on March 31, 2010; and





WHEREAS, Pursuant
to this Addendum, Lessor and Lessee desire to extend the term of the Lease for
an additional six and one-half months, and to modify certain other terms of the
Lease.





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:





1.  EXTENSION OF LEASE
TERM




The
initial term of the Lease is hereby extended for a term of six and one-half
months  (the “Extended Term”), commencing on April 1, 2010 and
expiring on October 15, 2010, upon the same terms, covenants and conditions as
are set forth in the Lease, as amended by this Addendum.




2.  RENT DURING EXTENDED
TERM




Notwithstanding
any provision of the Lease to the contrary, Lessee covenants to pay to Lessor,
as Monthly Rent for the Existing Demised Premises during the Extended Term
(“Extended Term Monthly Rent”), as follows:













Time
      Period
            Monthly
              Rent4/1/10  -  4/30/10
            $420,287.005/1/10  -  5/31/10
            $420,287.006/1/10  -  6/30/10
            $420,287.007/1/10  -  7/31/10
            $420,287.008/1/10  -  8/31/10
            $420,287.009/1/10  -  9/30/10
            $420,287.0010/1/10  -  10/15/10
            $420,287.00





Extended
Term Monthly Rent shall be payable in advance on the first day of each calendar
month during the Extended Term, without any rent credit, abatement or waiver by
Lessor.





3. NO PAYMENT OF OPERATING
EXPENSES OR OPERATING COSTS DURING EXTENDED TERM




Notwithstanding
any provision of the Lease to the contrary, during the Extended Term Lessee
shall not pay any Operating Expenses or Operating Costs.  Accordingly,
during the Extended Term, Section 5 of the Lease (entitled “Rent Escalation for
Increases in Expenses”) shall be void and of no further force or effect, except
that this Section shall continue to apply with respect to Lessee’s proportionate
share of Operating Expenses and Operating Costs due for the initial term of the
Lease.




4.  STORAGE SPACE
RENT




Notwithstanding
any provision of the Lease to the contrary, Lessee covenants to pay to Lessor
$468.32 per month, as monthly rent for the Storage Space during the time period
from April 1, 2010 to October 15, 2010, which rent shall be payable in advance
on the first day of each calendar month during the foregoing time period,
without any rent credit, abatement or waiver by Lessor.  Such monthly
rent for October, 2010 shall not be prorated, and therefore shall be in the
amount of $468.32.





5.  NO HOLDOVER
PERMITTED




Lessee
fully understands that it is of critical importance to Lessor that Lessor have
possession of the Existing Demised Premises no later than October 15, 2010, and
that Lessor may suffer substantial damages if Lessee were to hold over in the
Existing Demised Premises beyond October 15, 2010. Accordingly, notwithstanding
anything to the contrary in the Lease, Lessee shall have no right to hold over
in the Existing Demised Premises beyond October 15, 2010, and Lessee agrees to
surrender complete possession of the Existing Demised Premises to Lessor on or
before October 15, 2010 in the physical condition required by the applicable
provisions of the Lease.




2





6.  NO FURTHER OPTION TO EXTEND
TERM




Section
35 of the Lease (entitled “Option to Extend Term”) is hereby deleted in its
entirety and shall be of no further force or effect.







7.  SECURITY
DEPOSIT




Within
ten (10) days after the date of this Addendum, Lessee shall deliver to Lessor,
in form and content reasonably satisfactory to Lessor, documentation from the
issuer evidencing that the expiration date of the Letter of Credit currently
held by Lessor pursuant to Section 6.B of the Lease has been extended to
November 15, 2010.








8.  BROKER AND
AGENT




Lessor and Lessee each represents and
warrants one to another that, except as hereinafter set forth, neither of them
has employed any broker in carrying on the negotiations, or had any dealings
with any broker, relating to this Addendum.  Lessor represents that it
has employed its Management Agent as its broker, and Lessee represents that
Lincoln Property Company has co-brokered this transaction on behalf of
Lessee.  Lessor acknowledges that Lessor shall be responsible for any
commissions due to said brokers pursuant to separate
agreements.  Lessor shall indemnify and hold Lessee harmless, and
Lessee shall indemnify and hold Lessor harmless, from and against any claims or
claims for brokerage or other commission arising from or out of any breach of
the foregoing representation and warranty by the respective
indemnitors.





9.  LEASE PROVISIONS
APPLICABLE




Except to
the extent expressly modified by this Addendum, all of the terms and conditions
of the Lease, as amended or supplemented hereby, shall remain in full force and
effect.









(Signatures
on Following Page)





3







IN WITNESS WHEREOF, Lessor and Lessee
have caused this Addendum to be signed in their names by their duly authorized
representatives and delivered as their act and deed, intending to be legally
bound by its terms and provisions.





LESSOR





NEWLANDS BUILDING VENTURE,
LLC


a Maryland limited liability
company





By:          The
Chevy Chase Land Company


of Montgomery County,
Maryland,


Managing Member


Attest:








By:  /s/ David M.
Smith


Secretary                                                                              
Name: David M. Smith


(SEAL)                                                                                
Title: President














LESSEE:





Attest:                                                                                                   
COSTAR REALTY INFORMATION, INC.


a Delaware corporation








By:   /s/ Andrew
Florance


Secretary                                                                              Name:
Andrew Florance


(SEAL)                                                                              
  Title: CEO