The U.S. central bank's Federal Open Market Committee will release a statement at 12:30 p.m. In a Reuters poll, dealers expect the target for the benchmark fed funds rate to remain in the zero percent to 0.25 percent range. Federal Reserve Chairman Ben Bernanke will hold his first-ever news conference on monetary policy at 2:15 p.m. (1815 GMT).
Bernanke will likely make an argument that the economy still needs monetary policy support, and while he is not expected to signal a rush to tightening credit, he could discuss an exit to accommodative programs.
There's a good deal of uncertainty going into the meeting, and people have moved their positions to be as neutral as possible, said Tom Mangan, who helps oversee $2.4 billion as a money manager at James Investment Research Inc in Xenia, Ohio. I'd caution against being too bullish, since if there are any surprises that could be a catalyst for selling.
The Dow Jones industrial average <.DJI> was down 0.60 points at 12,594.77. The Standard & Poor's 500 Index <.SPX> was down 2.04 points, or 0.15 percent, at 1,345.20. The Nasdaq Composite Index <.IXIC> was down 1.97 points, or 0.07 percent, at 2,845.57.
The S&P 500 is up 7 percent so far in 2011 and hit a three-year high in the prior session. Recent gains have come on strong corporate results, with about 75 percent of reported S&P companies beating forecasts.
That trend continued on Wednesday, with Boeing Co , Whirlpool Corp and WellPoint Inc all topping analyst consensus expectations. Boeing, a Dow component, rose 1.2 percent to $76.43.
Praxair Inc , an industrial gas company, sank 3.9 percent to $103.95 after reporting results. The stock was the biggest loser on the S&P materials index <.GSPM>, which was the down the most among S&P sectors, down 1.5 percent.
On Tuesday the S&P 500 broke through the 1,344 level, seen as a key resistance. However, volume remained light ahead of Bernanke's comments.
I wish we saw a little higher volume, but it just shows how much uncertainty there is going into the Fed, said Matthew Keator, partner in the Keator Group, a wealth management firm in Lenox, Massachusetts.
Telecom stocks rose after CenturyLink Inc said it would buy Savvis Inc for about $2.5 billion in cash and stock. CenturyLink fell 1 percent to $39.92 while Savvis rose 9 percent to $39.27.
The S&P telecom services index <.GSPL> was the S&P's percentage leader, up 0.8 percent, while Verizon Communications Inc rose 1.4 percent to $38.16 as the Dow's biggest winner.
Also in deal news, Johnson & Johnson said it would buy Swiss medical devices maker Synthes Inc for $21.6 billion, the Dow component's largest ever buy. Shares of J&J fell 0.9 percent to $64.40.
(Editing by Kenneth Barry)