New York - Shares in groceries-selling retailers, including Walmart, British chain Tesco and France's Carrefour, tumbled on Friday after Amazon's announced it will acquire Whole Foods Market.
Amazon's deal to buy the upscale US grocery chain for $13.7bn throttled the broader retail sector on concerns the online retail giant will create an even tougher environment for food sellers.
US stocks were mixed, with the Nasdaq retreating but the Dow edging to a record due to gains by energy shares.
European markets rallied after eurozone ministers struck a long-delayed deal with Greece on Thursday to unlock badly-needed rescue cash.
The Amazon deal was the biggest story of the day, marking the technology giant's latest bold investment expected to disrupt grocers as well as the food industry.
Investors smiled on the two parties, sending Whole Foods' stock up 29.1% and Amazon 2.4% higher.
But the market punished other retailers, including Walmart, which lost 4.7%, supermarket chain Kroger, which shed 9.2%, big-box retailer Target fell 5.1%, and drugstore chain CVS Health dropped 3.8%.
In London, shares in Tesco finished the day down 4.9%.
Shares in Britain's largest retailer had earlier enjoyed solid gains as the firm had reported a 3.6% increase in sales worldwide. Even in Britain, where the market is facing headwinds from Brexit, sales grew by 1.6%.
"Tesco shares managed a spectacular 180 degree change in fortunes on Friday," said market analyst Jasper Lawler at London Capital Group.
"Investors flipped from satisfaction at the highest profits in seven years to fears that Amazon could knock Tesco off its perch as Britain's number one supermarket."
Amazon has a partnership with another British supermarket chain, Morrisons.
However, European stock markets rebounded overall from a sell-off the previous day. Equity traders have suffered a fraught week as the crisis engulfing Donald Trump picks up pace, technology firms tumbled from recent highs and energy plays were hammered by plunging oil prices.
But they shifted back into buying mode in Europe on Friday, with Frankfurt, London and Paris pushing higher ahead of the weekend following the latest Greece deal.Read Fin24's top stories trending on Twitter: