U.S. stocks slightly higher at midday ahead of Yellen conference

U.S. stocks traded higher around midday on Wednesday, as investors were eagerly awaiting Fed Chair Janet Yellen's news conference in the afternoon.

At noon, the Dow Jones Industrial Average added 16.85 points, or 0.09 percent, to 17,921.33. The S&P 500 edged up 0.78 point, or 0.04 percent, to 2,097.07. The Nasdaq Composite Index gained 4.88 points, or 0.10 percent, to 5,060.43.

The Fed kicked off its two-day meeting Tuesday. Though it is unlikely to raise interest rates at this meeting, investors still follow closely the central bank's statement after the meeting for clues on the timing of a possible rate hike.

Traders are also interested in officials' views on the U.S. economy. The Fed has said it will raise rates only when it sees an improvement in the economy.

"The Fed is likely to revise 2015 growth forecast lower, but the dots may not move. The median dot-plot forecast fell in December and fell even more in March. If the dots don't move today, if they continue to suggest two rate hikes in 2015 and four in 2016, it would send the message the Fed is very comfortable with its inflation forecast, despite the first quarter's growth disappointment," said Chris Low, chief economist at FTN Financial, in a note.

Greece remains in focus ahead of Thursday's Eurogroup meeting in Luxembourg, which many believe is the last chance before Greece 's EU bailout expires by the end of June.

One of Greece's leading economists, Professor Michalis Psalidopoulos, was appointed as the country's new representative to the International Monetary Fund, a Greek Finance Ministry press release said Wednesday.

The decision was made when a debt deal with international lenders to avoid a Greek default was still up in the air. Endite