Wall Street flat in choppy trade ECB in focus

US stocks were flat in volatile trade on Wednesday as investors awaited clarity on media reports that the European Central Bank would, with broad support from its council members, unveil an unlimited, sterilized program of bond purchases.

Bloomberg reported that Draghi's plan would involve unlimited buying of government bonds. The ECB has been expected to be cautious about disclosing the size of its bond-buying, given opposition from Germany's central bank.

The report comes ahead of an ECB meeting on Thursday and the Federal Open Market Committee's own policy meeting next week on Sept 12-13.

"I think there's a very significant risk that there's going to be a sell-the-news reaction. Even if the ECB comes with some kind of bond-buying program and the Fed announces some form of additional stimulus, I think there's a pretty good chance that the market will sell that news," said James Dailey, portfolio manger at TEAM Asset Strategy fund in Harrisburg, Pennsylvania.

FedEx Corp, the world's No. 2 package delivery company, cut its profit outlook for the current quarter, saying weakness in the global economy was hurting demand for overnight international shipments more than anticipated. The announcement was made after the closing bell on Tuesday.

Nokia and Microsoft Corp will take the wraps off the struggling European company's most powerful smartphone on Wednesday, in what may be their last major shot at winning back a market dominated by Apple , Samsung and Google .

Facebook Inc promised not to sell stock to cover a nearly $2 billion tax bill and said it will allow employees to cash in their stock weeks ahead of schedule, moving to soothe nervous investors and its own staff as its share price spirals downward from its $38 IPO price.

The Dow Jones industrial average was up 15.14 points, or 0.12 percent, at 13,051.08. The Standard & Poor's 500 Index was down 0.47 points, or 0.03 percent, at 1,404.47. The Nasdaq Composite Index was down 4.40 points, or 0.14 percent, at 3,070.66.