Whole Foods (WFM) shareholders and the Federal Trade Commission approved the Whole Foods-Amazon.com (AMZN) - Get Report merger on Wednesday, but that was the easy part.

The $13.7 billion deal that was first announced in June was obviously going to be approved, but now comes the hard part: Amazon has to turn around Whole Foods, which "by every measurement is a failing retailer," ex-Amazon executive Brittain Ladd said. Brittain worked on the global expansion of AmazonFresh and predicted in a paper written back in 2013 that Amazon would buy Whole Foods.

While Amazon and its fearless leader Jeff Bezos are generally thought of as undefeatable, this acquisition is a big undertaking and has to be done right, Ladd said. "I continue to support the acquisition by Amazon but I am cognizant of the fact that if Amazon isn't careful, Whole Foods has the potential to become Amazon's bridge too far," he explained.

The nearly $14 billion Whole Foods acquisition is Amazon's largest deal to date. Previously, the title was held by the $1.2 billion the company spent on shoe store Zappos in late 2009. With larger acquisitions come larger responsibilities. The grocery sector was already a hot bed for competition and the Amazon-Whole Foods deal just made grocery players that much more paranoid.

"Walmart (WMT) - Get Report , Kroger (KR) - Get Report , Aldi, Lidl and other retailers are accelerating their investments to increase their competitive advantages," Ladd said. "In just a few short months from the time Amazon announced they wanted to acquire Whole Foods, competition has increased with Walmart and other retailers announcing increased sales and new strategies."

Walmart announced a new partnership with Alphabet's (GOOGL) - Get Report Google on Wednesday to allow Walmart shoppers to easily purchase items through the voice-activated smart speaker Google Home. This is a direct attack on Amazon, which already allows people to shop on its range of smart speaker devices through its Alexa digital assistant.

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"Victory is anything but assured for Amazon as the companies they will compete against aren't backing down. The grocery industry is very, very challenging and Amazon has never competed in an industry with margins as low as groceries," Ladd said in conclusion.

Meanwhile, TheStreet reveals who else Amazon should buy.

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