Costco Wholesale Corporation, doing business as Costco, is an American multinational corporation which operates a chain of membership-only warehouse clubs.As of 2015, Costco was the second largest retailer in the world after Walmart, and as of 2016, Costco was the world's largest retailer of choice and prime beef, organic foods, rotisserie chicken, and wine. As of 2019, Costco is ranked #14 on the Fortune 500 rankings of the largest United States corporations by total revenue.