Alcoa led a rally in companies that make basic materials after the aluminum maker reported earnings that were better than investors were expecting. Alcoa rose 4 per cent.
Technology stocks, which fell sharply over the past week, also rose. Facebook gained 5 per cent.
The Standard & Poor's 500 index rose six points, or 0.3 per cent, to 1,858 as of noon (1600 GMT) Wednesday.
The Dow Jones industrial average rose 59 points, or 0.4 per cent, to 16,315. The Nasdaq composite rose 28 points, or 0.7 per cent, to 4,141.
Bond prices fell. The yield on the 10-year Treasury note rose to 2.71 per cent.