U.S. stocks closed mixed on Wednesday, coming off morning highs amid economic reports and central bank news.
"I think all eyes will be on the ECB, especially on the heels of the Jackson Hole meeting," Todd Salamone, senior vice president at Schaeffer's Investment Research, said.
The European Central Bank is scheduled to hold its monthly policy meeting on Thursday and may announce the launch of a bond-buying program.
"Obviously that's going to be very, very important," Scott Brown, chief economist at Raymond James, said. "Markets have priced in some quantitative easing from the ECB, so they may be disappointed."
Apple had its worst day in more than 7 months as shares lost more than 4 percent, earlier sending the Nasdaq lower almost 0.70 percent and the S&P 500 down 0.13 percent.
"I think that Apple is just being used as an excuse for the market going down," Marc Chaikin of Chaikin Analytics said. "I don't think the news out of Samsung is really that significant."
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Samsung revealed two large-screen phones and a virtual reality device on Wednesday at simultaneous events in New York, Beijing and Berlin, ahead of Apple's expected unveiling of the iPhone 6 next week.
With market composite volume slightly below average, Salamone also noted a hesitancy to buy and a tendency to sell in the markets on Wednesday.
"I think a lot of people are looking at their gains this year and taking a little off the table," Kim Forrest, senior equity analyst at Fort Pitt Capital, said. "Even though the Ukraine situation seems to be coming off the boil, investors don't seem to be happy about the data we got today."
On Wednesday, stocks held to earlier trends after July factory orders rose in-line with expectations, strong U.S. auto sales for August, and the release of the Fed's Beige Book, which found modest to moderate economic expansion.
"It takes a long time to disseminate [that news]," Art Hogan, chief market strategist at Wunderlich Securities said. "I would say that [the ECB] is the next signpost up ahead. We'll be on the edge of our seats for any acknowledgement of a purchase plan."