Amazon.com Inc.’s AMZN +2.31% purchase of Whole Foods Market Inc. WFM 29.63% isn’t just a $13.7 billion bet that many shoppers still want to buy groceries at physical stores. It is a direct strike at the world’s biggest retailer: Wal-Mart Stores Inc. WMT -4.80% .  Wal-Mart generates more than half of its $486 billion in annual revenue from groceries and is the country’s largest grocer. Shoppers’ penchant for picking their own produce and the unprofitable nature of delivering

fresh food to homes has given Wal-Mart a rare edge over Amazon and breathing room while ramping up its digital business with a string of e-commerce acquisitions and other investments. “I feel great about how we are positioned with 4,700 stores,” Wal-Mart’s e-commerce chief Marc Lore said Friday in an interview. “It’s fun playing offense and I like the fact that we aren’t chasing.” READ MORE