Sears, Roebuck & Company, also known simply as Sears, is an American department store chain founded by Richard Warren Sears and Alvah Curtis Roebuck in 1886. Formerly based at the Sears Tower in Chicago and currently headquartered in Hoffman Estates, Illinois, it began as a mail ordering catalog company and began opening retail locations in 1925. The company was bought by the American big box chain Kmart in 2005, which had just emerged from bankruptcy at the time and renamed itself Sears Holdings upon completion of the merger. In terms of domestic revenue, Sears was the largest retailer in the United States until October 1989, when Walmart surpassed the record. It is currently the fifth-largest American department store company by sales as of October 2013 (behind Walmart, Target, Best Buy, and The Home Depot), and the twelfth-largest retailer in the country overall. Sears operates divisions in Canada and Mexico, as well as several other subsidiaries within its brand.