Shares of several grocery store chains, including Kroger and Sprouts Farmers Market, dipped on Monday after Amazon’s (AMZN - Free Report) acquisition of Whole Foods (WFM - Free Report) officially went into effect. 

The online retail giant’s $13.7 billion purchase of the organic grocer helped send rival grocery chains stocks plummeting last week after the FTC approval was finalized. One of the biggest causes of concern for fellow grocery stores, at least initially, was the fact that Amazon announced it would lower prices on many items at Whole Foods.

“Everybody should be able to eat Whole Foods Market quality – we will lower prices without compromising Whole Foods Market’s long-held commitment to the highest standards,” CEO of Amazon Worldwide Consumer Jeff Wilke said in a statement last week.

“To get started, we’re going to lower prices beginning Monday on a selection of best-selling grocery staples, including Whole Trade organic bananas, responsibly-farmed salmon, organic large brown eggs, animal-welfare-rated 85% lean ground beef, and more.”

Jeff Bezos’ company did precisely what it said it would. Amazon lowered a ton of prices at Whole Foods on Monday. The total price of a 15-item grocery purchase at a Brooklyn, New York-based Whole Foods fell by almost 23% on Monday, according to a Business Insider article.

“Whole Foods + Amazon" signs can now be seen throughout Whole Foods locations and new discounted tags labeled "New Lower Price," are also widespread. Prices of items such as milk, cheese, meat, fish, eggs, and many more commonly purchased foods have also already been cut.

Whole Foods is far from the biggest grocery store chain in the U.S., with only 470 locations. But the size and reach of Amazon has already enabled it to lower prices at the notoriously high-priced grocer over night. And investors continued to flee from grocery store stocks on Monday as the initial price cuts went into effect.

Shares of Target (TGT - Free Report) , with its large grocery business, dipped by 1.04%, while Kroger (KR - Free Report) , which owns multiple grocery subsidiaries, dipped marginally.

Less well-known chain Sprouts Farmers Market (SFM - Free Report) saw its stock price crash 9.71%, while Ingles Markets (IMKTA - Free Report) sunk by 9.69%. SUPERVALU Inc. (SVU - Free Report) and Smart & Final Stores (SFS - Free Report) both saw their stock prices fall by more than 2%, while Weis Markets stock dipped by 1.60%.

Bottom Line

Grocery Store chains most likely don’t need to fear for their short-term stability or even viability. But, if the industry does not begin to make changes to their business models going forward, Amazon’s Whole Foods and its new lower prices could make life a lot harder—especially if investors continue to flee the allies.