However, excluding the adverse impact of foreign currency fluctuations and deflation in gasoline prices, Costco's comps for the month under review rose 4%. Costco, which competes with Wal-Mart Stores Inc. WMT , currently operates 706 warehouses, which include 494 in the U.S. and Puerto Rico, 90 in Canada, 36 in Mexico, 27 in the U.K., 25 in Japan, 12 in Korea, 12 in Taiwan, 8 in Australia, and 2 in Spain. Costco Wholesale CorporationCOST disappointed investors once again as it reported flat comparable-store sales (comps) for the month of May (the four-week period ended May 29, 2016).