The Pennsylvania Real Estate Investment Trust (PREIT) (NYSE: PEI) is one of the first publicly traded real estate investment trusts, established in 1960 by Sylvan M. Cohen (died September 8, 2001). The PREIT corporate offices are located in Philadelphia, Pennsylvania. The company owns and operates over 25 million square feet of retail focusing on shopping centers in the eastern United States, particularly in the mid-Atlantic states of Pennsylvania, New Jersey and Maryland. The company has large number of assets in the Philadelphia and Washington DC metro markets. In 1997 PREIT merged with the Rubin Organization, a commercial property development and management firm. In 2003 the firm changed its strategic focus from a diversified property base to retail. During that year PREIT acquired six shopping malls from The Rouse Company, sold several multifamily residential properties, and completed a merger with Crown American Realty Trust.