Shares of a number of companies that sell groceries, including Kroger (KR), Sprouts Farmers Market (SFM) and Costco (COST), are moving lower after Amazon (AMZN) announced that its acquisition of Whole Foods Market (WFM) will close on Monday August 28.

As part of the announcement, Jeff Wilke, CEO of Amazon Worldwide Consumer, said, “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. And this is just the beginning – we will make Amazon Prime the customer rewards program at Whole Foods Market and continuously lower prices as we invent together.

There is significant work and opportunity ahead, and we’re thrilled to get started.”