CoStar Group Files Registration Statement for Public Offering of 1,250,000 Shares of Common Stock.

Business Editors

BETHESDA, Md.--(BUSINESS WIRE)--July 2, 2003

CoStar Group, Inc. (NASDAQ: CSGP), the leading provider of information services to commercial real estate professionals in the United States and the United Kingdom, announced today it has filed with the Securities and Exchange Commission a registration statement for a proposed public offering of 1,250,000 shares of Common Stock. All of the shares to be offered will be sold by the Company. In addition, the Company will grant the underwriters an option to purchase up to 187,500 additional shares to cover underwriters' over-allotments.

The net proceeds to the Company will be used to fund all or a portion of the costs of future strategic acquisitions, although the Company has no present understanding or agreement relating to any specific acquisition or investment; expand into new and existing markets; develop and facilitate distribution of new services; and fund working capital and other general corporate purposes.

The proposed offering will be managed by Needham & Company, Inc. and JMP Securities LLC.

A copy of the preliminary prospectus can be obtained from Needham & Company, Inc., 445 Park Avenue, New York, NY 10022; or JMP Securities LLC, One Embarcadero Center, Suite 2100, San Francisco, CA 94111.

A registration statement relating to these securities has been filed with the Securities and Exchange Commission but has not yet become effective. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. This news release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.