CoStar Group, Inc.
President and CEO
Rings The NASDAQ Stock Market Opening Bell

Friday, January 14, 2005
at NASDAQ's MarketSite
in New York City.

The NASDAQ Stock Market is proud to welcome CoStar, Inc. [CSGP] and its CEO Andrew C. Florance to the market open in honor of the company joining the NASDAQ Financial-100 Index. The NASDAQ Financial-100 Index includes 100 of the largest domestic and international financial companies listed on The NASDAQ Stock Market based on market capitalization. The Index contains financial institutions and related holding companies, insurance companies, real estate companies, broker dealers, investment companies and financial services.

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.

Click for larger pictures of the NASDAQ MarketSite. Additional Photographs for 01/14/2005 Download Hi-Res Quality Photo of this NASDAQ Market Open - Pictured: CoStar Group, Inc. [CSGP] President and CEO Rings The NASDAQ Stock Market Opening Bell These photos are Copyright 2005, Getty Images for The Nasdaq Stock Market Inc. and available for re-publication by the news media only. Any commercial use is strictly prohibited without the prior written consent of Getty Images and The Nasdaq Stock Market Inc. © Copyright 2005, Getty Images for NASDAQ The Nasdaq Stock Market, Inc. Reprinted with the permission of The Nasdaq Stock Market, Inc.