PRESS RELEASE DETAIL


Dec 27, 2007

Michael Arabe, CoStar SVP of Sales, Resigns

2004-05-21 2004 Michael Arabe, CoStar SVP of Sales, Resigns Company Believes Revenue Expectations Are on Track for 2004

BETHESDA, MD -- CoStar ...

2004-05-21 2004 Michael Arabe, CoStar SVP of Sales, Resigns Company Believes Revenue Expectations Are on Track for 2004

BETHESDA, MD -- CoStar Group, Inc. (NASDAQ: CSGP), today announced it has accepted the resignation of Michael Arabe, who is leaving the company for personal reasons.

Arabe had been with CoStar and a predecessor company, COMPS.com, since 1989, and most recently served as Senior Vice President of Sales and Customer Service since January 2003.

Stephen B. Alliegro, CoStar's Vice President of Sales for the eastern region, will assume Arabe's responsibilities on an interim basis. Alliegro has been with CoStar since 1998 and has consistently produced strong revenue growth while expanding his geographic responsibilities. The Company plans to conduct a search for a sales management executive experienced in managing a large, geographically dispersed sales organization.

"I want to thank Michael for his significant contributions in positioning our company for continued aggressive growth," stated CoStar President & CEO Andrew C. Florance. "We respect his desire to spend more time with his family, and wish him the best in future endeavors."

The Company does not expect Arabe's departure to have an adverse impact on its revenue expectations. "We continue to expect overall sequential quarterly revenue growth of approximately 4% for the second quarter of 2004 and annual revenue growth of approximately 16% for 2004 compared to 2003," stated Frank A. Carchedi, CoStar's Chief Financial Officer.

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 over 50 U.S. markets, London and the United Kingdom. Based in Bethesda, MD, the company has approximately 900 employees in 37 offices throughout the United States and the United Kingdom, including the largest professional research organization in the industry.

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 from those discussed in the forward-looking statements 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 March 31, 2004, under the heading "Risk Factors." In addition to these statements, there can be no assurance that CoStar's quarterly sequential revenue growth rate for the second quarter of 2004 or annual sequential revenue growth rate will be as stated in this press release. All forward-looking statements are based on information available to CoStar on the date hereof, and CoStar assumes no obligation to update such statements.
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