PRESS RELEASE DETAIL


Jan 31, 2008

CoStar Group, Inc. Announces Proposed Underwritten Offering by Certain of its Stockholders

2000-08-02 2000 CoStar Group, Inc. Announces Proposed Underwritten Offering by Certain of its Stockholders

BETHESDA, MD -- CoStar Group, Inc. (Nasdaq:...

2000-08-02 2000 CoStar Group, Inc. Announces Proposed Underwritten Offering by Certain of its Stockholders

BETHESDA, MD -- CoStar Group, Inc. (Nasdaq: CSGP), http://www.costargroup.com, today announced that it expects that up to 1,123,855 shares of its common stock will be offered by certain of its selling stockholders in an underwritten offering led by Donaldson, Lufkin & Jenrette. The shares are included in a shelf registration statement filed with the Securities and Exchange Commission on June 16, 2000 and declared effective on August 2, 2000. The terms of any underwriting arrangements, once finalized, would be disclosed in a prospectus supplement filed with the SEC. We expect the proposed underwritten offering to be completed during August. CoStar Group, Inc. will not receive any proceeds from this offering.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sales of these securities in any jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. The proposed offering will be made by means of a prospectus supplement to a prospectus that is part of CoStar's shelf registration statement previously filed with the Securities and Exchange Commission. Copies of the prospectus and the prospectus supplement, if any, can be obtained from Donaldson, Lufkin & Jenrette.

About CoStar Group, Inc.

Headquartered in Bethesda, MD, CoStar Group, Inc. is the leading provider of information services to the U.S. commercial real estate industry. CoStar's suite of products offers customers access via the Internet to the most comprehensive, verified database of commercial real estate information in over 50 U.S. markets. The company has more than 1,000 employees and contractors nationally, including over 700 highly trained commercial real estate research professionals in 27 offices.

This news release includes "forward-looking statements," which involve many risks and uncertainties that could cause actual results to differ materially from these statements. Important factors that could cause actual results to differ materially include, but are not limited to, those listed in CoStar's Form 10-K for the year ended December 31, 1999 and its Registration Statement on Form S-3 filed on June 16, 2000.
'