Whole Foods! Competitors now include big box and discount retailers who have made a foray into the grocery business. Currently, the United States! Largest grocer is Wal-Mart. Not only does Wal-Mart compete in the standard supermarket industry, but it has even begun offering natural and organic products in its supercenter stores. Other discount retailers now competing in the supermarket industry include Target, Sam’s Club, and Costco. All of these retailers offer grocery products, generally at a lower price than what one would find at Whole Foods.