CoStar Signs World's Largest Real Estate Services Firm To Long-Term Renewal Agreement.

Business Editors

BETHESDA, Md.--(BUSINESS WIRE)--Dec. 8, 2003

CB Richard Ellis Selects CoStar to Provide Comprehensive Leasing, Sales And Tenant Data to 3,900 Professionals Nationwide

CoStar Group, Inc. (Nasdaq:CSGP) today announced it has signed a national, multi-year renewal agreement with CB Richard Ellis, the world's largest commercial real estate services firm, to provide its full suite of information services to 3,900 CB Richard Ellis professionals in 117 offices nationwide.

CoStar Group is the leading provider of information services to the commercial real estate industry in the United States and the United Kingdom.

The new agreement combines and expands the separate agreements signed previously by CB Richard Ellis and Insignia/ESG, Inc., which was acquired by CB Richard Ellis in July 2003. Under the new agreement, all of the former Insignia/ESG professionals at CB Richard Ellis will have access to a broader array of CoStar services than was provided for under the previous license. In addition, the former Insignia/ESG professionals in Atlanta and Cleveland will now have access to CoStar services that were not provided under Insignia/ESG's license agreement.

Under terms of the agreement, most of CB Richard Ellis's U.S. professionals will have direct access to the full suite of CoStar information services for their local market, including CoStar Property Professional(TM), which provides a complete inventory of office and industrial properties and sophisticated software to research leasing options, analyze market conditions and position properties in the marketplace; and CoStar Tenant(R), a database of the detailed tenant information for prospecting and analyses. Under the multi-year agreement, CB Richard Ellis professionals also will have access to CoStar COMPS Professional(TM), the only verified national database of commercial comparable sales transactions; and CoStar Exchange(R), the largest verified database of commercial properties for sale.

In addition, many of CB Richard Ellis's global corporate services professionals will have access to complete national CoStar Property data, enabling them to better serve their multi-market clients.

"We're thrilled to continue our longstanding relationship with CB Richard Ellis," stated Andrew C. Florance, CoStar's president & CEO. "It's an honor to be selected once again as a key data service for the world's largest real estate services firm, and we're pleased to support its growth."

CB Richard Ellis will continue to access CoStar information in the U.K. under a separate license with CoStar's Focus Information subsidiary.

About CoStar Group, Inc.

CoStar Group, Inc. (NASDAQ:CSGP) is the leading provider of information services to commercial real estate professionals in the United States and the United Kingdom. CoStar's suite of services offers customers access via the Internet to the most comprehensive database of commercial real estate information on 50 U.S. markets, London and the United Kingdom. Based in Bethesda, MD, the company has approximately 850 employees in 35 offices throughout the United States and the United Kingdom, including the largest professional research organization in the industry.

About CB Richard Ellis

CB Richard Ellis is the global leader in commercial real estate. With approximately 14,000 employees in approximately 250 offices across 48 countries, CB Richard Ellis completes more successful transactions each year - with clients from the gamut of industries - than any other firm in the world. Services include property sales and leasing, property management, corporate services and facilities management, mortgage banking, investment management, capital markets, appraisal/valuation, research and consulting.

This news release includes "forward-looking statements" including, without limitation, statements regarding CoStar's expectations, beliefs, intentions or strategies regarding the future. These statements are subject to many risks and uncertainties that could cause actual results to differ materially from these statements. More information about potential factors that could cause actual results to differ materially include, but are not limited to, those stated in CoStar's filings from time to time with the Securities and Exchange Commission, including CoStar's Form 10-Q for the quarter ended September 30, 2003, under the heading "Risk Factors." All forward-looking statements are based on information available to CoStar on the date hereof, and CoStar assumes no obligation to update such statements.