Bottom pickers beware. 

Ahead of Amazon.com's (AMZN) Prime Day, TheStreet's founder and Action Alerts PLUS portfolio manager Jim Cramer expects Amazon's sales to be up 20% year over year and brick-and-mortar retailers to get hammered.

"Maybe Wednesday will create a soft bottom in retail [stocks] and you'll want to come in and start buying," Cramer said.

Amazon is hosting its third annual Prime Day sale this week and a number of big retail names are responding with sales of their own.

Amazon's massive sales event for Prime members will kick off on July 10 at 9 p.m. ET and run through July 12 at 3 a.m. ET, with new deals being offered every five minutes. People who aren't Prime members can sign up for a membership on or before July 11 to take part in the big sales event.

The success of Prime Day over its previous two years has led to other retailers getting a bit jealous and putting on their own sales events at the same time.

During last year's Prime Day event, Walmart (WMT) notably launched its "Dare to Compare" online sale that showed items on their site that beat the price of the item on the site of one of their main competitors, including Amazon. "Walmart never specifically stated they were trying to directly compete with Amazon with this sale, but the evidence seems pretty clear," BestBlackFriday.com's Phillip Dengler said.

This year, Walmart has refrained from promoting its "Dare to Compare" page, resorting to promoting generic "Huge Summer Savings" sales instead.

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