Report: Amazon considering 3,000 cashier-free stores by 2021

Amazon is considering a plan to open 3,000 more cashierless "Amazon Go" stores within the next 3 years, Bloomberg reports.

Why it matters: A few of the automated grocery stores are already open in the U.S., but a major push like this could give traditional grocery and convenience stores serious checkout line-free competition. Shares of Kroger and Walmart moved lower on the news. Go deeper: Amazon Go is a "fist" aimed at the convenience store industry