Retailers such as Best Buy, Blockbuster and Target are among the customers that use NRB's data, said Andrew C. Florance, president and CEO of CoStar. NRB's products include the Shopping Center Directory and analytic reports.

As part of the deal, CoStar will be able to use demographic information supplied by Claritas via a licensing agreement between the two companies. "With this deal, we are accessing the leading demographic data in the retail sector and making it available to the majority of our customers," Florance says.

CoStar plans to expand its retail service as it enters 21 new markets this year and expects to add 200,000 retail properties to its database this year, bringing its total to 270,000. The company will add those listings through the acquisition of another firm and/or field research. Before the NRB acquisition, CoStar's database already tracked 72,000 properties.