In reaction to the news, shares of largely brick-and-mortar retailers already threatened by Amazon’s dominance in e-commerce opened significantly lower in trading Friday. Target opened 12% lower, Walmart was down 5%, Costco was down 6%, while SuperValu had fallen 19.95% on the news. Kroger also fell 15%, making it the worst performing stock on the S&P 500 and extending its losses from a day earlier when the company reported declines in first quarter profits.

In total, those five grocery chains shed about $26.7 billion in market capitalization between the market’s close Thursday and Friday morning, as investors worried that Amazon deeper push into the industry could be a death knell for some.

Amazon was up about 3% in trading Friday, while Whole Foods was up 27% to just below the $42 per share Amazon will be paying to buy the grocery chain.

But Kroger’s market capitalization fell to $19.4 billion, Walmart’s fell to $222.7 billion, Target’s dropped to $13.4 billion, Costco to $74 billion, and SuperValu to $888.8 million.

The worries weren’t just contained to U.S. markets. Some investors in the U.K. and Europe also saw the purchase as a sign that Amazon could take its grocery ambitions global. Shares of French retailer Carrefour fell sharply on the news, about 4%, while in London, Tesco shed 6% and Sainsbury dropped 5%.

But the sell off may not be entirely attributed to Amazon’s purchase of Whole Foods. Investors and their outlook on the grocery store space had already darkened during the week. Not only did Kroger’s weak earnings report fan worries about the industry as a whole, but major new competitors also stepped into the arena: German grocery chain Aldi said Monday tat it would open some 900 stores in the U.S. by the end of 2022, while fellow German grocer Lidl opened its first U.S. location on Thursday.