Updated from 6:01 a.m. ET
 
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Here are five things you must know for Wednesday, Aug. 23:
 
1. -- U.S. stock futures on Wednesday, Aug. 23, were down modestly following a strong rally during the previous session and after Donald Trump threatened to pull the U.S. out of the North American Free Trade Agreement.
 
The president said late Tuesday that he thinks the U.S. will "end up probably terminating" NAFTA with Canada and Mexico "at some point."
 
The three countries began formal negotiations last week to rework the 23-year-old trade pact. Trump slammed the agreement during his campaign as the "worst" in history.
 
The Dow Jones Industrial Average on Tuesday, Aug. 22, gained 0.90%, or 196 points,  for one of its best daily performances this summer. The S&P 500 added 0.99% and the Nasdaq gained 1.36%.
 
On Wednesday, the economic calendar in the U.S. includes the PMI Composite Flash for August at 9:45 a.m. ET, New Home Sales for July at 10 a.m., and Oil Inventories for the week ended Aug. 18, at 10:30 a.m.
 
2. -- Walmart Stores Inc. ( WMT) , under a new partnership with Alphabet Inc.'s ( GOOGL)  Google, will allow shoppers to make purchases through the voice-activated device Google Home, the Google Express app or its website.
 
A Google assistant, which is tantamount to an online personal shopper, will be assigned to each customer to fulfill the order and set it up to be delivered to their homes.
 
"I think this gives us a look into the future of shopping, yes," Walmart president and CEO of U.S. e-commerce, Marc Lore, told TheStreet in an interview. "I think with the advancements in artificial intelligence voice ordering will get better over time."
 
The initiative launches on Sept. 1, and will be offered with a free one- to three-day shipping service, depending on the size of the order.

Shares of Walmart rose 0.5% in premarket trading on Wednesday.

Alphabet is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells GOOGL? Learn more now

3. -- Apple Inc. (AAPL) has scrapped the idea of an Apple-branded autonomous vehicle and is instead working on the underlying technology that allows a car to drive itself, the New York Times reported. To that end, the company is developing a self-driving shuttle service that ferries employees from one Apple building to another, said sources.

The shuttle likely will be a commercial vehicle from an automaker and Apple will use it to test the autonomous driving technology that it develops, according to the Times.

Apple's testing vehicles will carry employees between its various Silicon Valley offices. The new effort is called PAIL, short for Palo Alto to Infinite Loop, the address of the company's main office in Cupertino, Calif. The company's in-house shuttle service isn't operational yet.

Apple is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells AAPL? Learn more now.  

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