DDR Corp. is a publicly traded real estate investment trust that owns and manages value-oriented, open-air retail shopping centers, or "power centers" in the United States mainland and Puerto Rico. The company was founded in 1965 and is based in Beachwood, Ohio, an eastern suburb of Greater Cleveland. It operates in approximately 40 continental U.S. states and in the U.S. Commonwealth of Puerto Rico. The companys roots go back to a group of companies established by lawyer and single family home builder Bertram Wolstein, an alumnus of Cleveland–Marshall College of Law. In 1965 he switched to commercial real estate and began a partnership with Kmart, with the first one built in 1965. DDR filed its initial public offering of Common Shares on February 2, 1993. The price at that time was $22.00 per share, and the company began trading on the New York Stock Exchange under the ticker symbol DDR on February 2, 1993.