The online grocery company soared the last time Amazon leveled a major challenge to its business. How will it respond to the latest salvo?

Discover why Amazon.com, Inc.'s growth strategies and valuation position it as a top investment pick over Walmart Inc. Click for my AMZN/WMT comparison.

Walmart announced yesterday it is partnering with Instacart. The move is another effort by Walmart to compete with Amazon’s Whole Foods division that now has same-day and one-day Prime delivery.

Same-day grocery delivery explodes to 2,300 cities, sending shockwaves through Walmart, Kroger, and food delivery stocks.

On Instacart, you’re not limited to a single retailer, the way you are with Walmart’s service. Instacart Express works with tons of your favorite grocery stores—Aldi, Big Lots, Hy-Vee ...

Amazon AMZN will broaden its grocery delivery offering to reach more than 2,300 cities and towns in the U.S. by the end of the year, the e-commerce giant said Wednesday. Amazon stock gained while shares of a rival, Instacart parent company Maplebear CART, fell sharply.