Wal-Mart Stores is the world's biggest retailer, operating a number of retailing formats in all 50 states in the US. The company operates three divisions: The Wal-Mart Stores, which includes its discount stores, Supercenters and Neighborhood Markets, in the US; The SAM's CLUB warehouse membership clubs; and the International business, which includes all of its operations in Argentina, Brazil, Canada, China, Japan, Germany, Korea, Mexico, Puerto Rico and the United Kingdom. In 1999, Wal-Mart completed its purchase of UK supermarket, ASDA.