Hope that they might be next.
Bankers report an upsurge in requests from their retail clients asking that they put a call in to see if Amazon would be interested in acquiring them, too.
At the same time, investors, analysts and consulting firms have engaged in an elaborate guessing game about which targets might be on the radar of Amazon chief executive Jeff Bezos now that the king of US ecommerce has shown himself interested in bricks and mortar stores.
The calls to mergers and acquisitions bankers have ratcheted up this summer, according to more than five advisers who were contacted by clients. Requests that bankers put out feelers to Amazon have come from apparel, grocery and convenience store companies, they say.
"Everything is Amazon these days," says a senior consumer and retail banker in New York, who asked not to be named as they are not authorised to talk about clients to the media.
While unconventional, the idea of reaching out to a single potential buyer proved a winning strategy for Whole Foods.
The company's executives, under pressure from activist investors, called Amazon after they spotted a media report suggesting the online retailer had considered buying their company. John Mackey, Whole Foods' chief executive, described the months leading to Amazon's $13.7bn offer as a "whirlwind romance".
"All these desperate retail companies think that the solution to their problems will be solved by Bezos . . . they are all praying for a new 'Amazonian' era of retail . . . in which they are members of the [Bezos] club," says another banker.
Amazon declined to comment for this story.
Before Whole Foods, Amazon's financial bets were smaller. The Seattle-based ecommerce giant has made about 130 acquisitions or investments since its debut in 1995, in a wide range of industries from books and music to cloud computing. Its largest acquisition until this year was Twitch, a site where millions of regular visitors watch other people play video games, for $970m in 2014.
Analysts are also speculating about which companies Mr Bezos might target next.
Aaron Turner, analyst at Wedbush Securities, says the company could buy GrubHub, the fast-growing US food delivery start-up, to move further into food and create a "dominant force in restaurant delivery".
"This is not imminent by any means," he cautions. "But clearly [Amazon] is laser-focused on food, specifically perishable food." Mr Turner says Amazon could buy GrubHub for about $4.5bn, giving it a network of 50,000 restaurants and nearly 9m active diners.
Nordstrom shoppers are twice as likely as the average person to shop at Whole Foods, says Mr Glueck, while Warby Parker, the trendy eyewear retailer, would help capture coveted millennial consumers, he says.
The interest in Amazon comes as traditional retail and consumer companies are grappling with enormous changes in how people shop and what they want to buy. US department store sales have dropped 18 per cent since 2010, according to Bank of America estimates, while PwC expects at least 90m sq ft of retail space will be closed this year.
Amazon has been rumoured as a white knight for underperforming retailers in the past, although several of the bankers contacted by clients are pushing back. Their advice has been instead to focus on improving margins by restructuring the business or cutting costs by merging with rivals, rather than banking on the idea of Amazon saving them.
"Amazon is on its own path and will not just keep on buying for the sake of it," says a banker working in the retail sector. "Historically they have been deal shy and anyone thinking that they will be saved from Amazon is wrong."
And some industry veterans are cautious too. "Jeff thinks differently than us," says a senior executive at one of the largest US grocers. "I think he'll be doing something completely different."