PRESS RELEASE DETAIL


Dec 21, 2007

CoStar Group To Open NASDAQ Stock Market

2005-01-14 2005 CoStar Group To Open NASDAQ Stock Market Company Celebrates Addition to the NASDAQ Financial-100

BETHESDA, MD -- CoStar Group, ...

2005-01-14 2005 CoStar Group To Open NASDAQ Stock Market Company Celebrates Addition to the NASDAQ Financial-100

BETHESDA, MD -- CoStar Group, Inc. (NASDAQ: CSGP), the leading provider of information services to the commercial real estate industry, announced that Andrew C. Florance, President & CEO, will join Bruce Aust, NASDAQ Executive Vice President, to open The NASDAQ Stock Market today at 9:30 a.m. Eastern time.

"We are honored to participate in the prestigious NASDAQ Opening Bell ceremony," stated CoStar Group President & CEO Andrew C. Florance. "It is very gratifying to have such prominent recognition of our strong financial achievement."

CoStar has produced strong revenue and earnings growth since its IPO in 1998. In its most recent reported public financials, the Company had over $100 million in annualized revenues, and its market capitalization currently has grown to over $800 million.

As a result, on July 1, 2004, CoStar was named to the NASDAQ Financial-100 Index, which includes 100 of the largest domestic and international financial companies listed on The NASDAQ Stock Market, based on market capitalization.

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 950 employees 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 September 30, 2004, 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.
'