By Kate Gibson, MarketWatch NEW YORK (MarketWatch) -- U.S. stocks opened sharply higher Wednesday, bouncing back after a five-session losing run, with aluminum maker Alcoa Inc.'s unexpected first-quarter profit cheering investors. The Dow Jones Industrial Average (DJI) rose 109.4 points to 12,825.30, as shares of Alcoa (AA) rose the most among its 30 components, rallying 7.7%. The S&P 500 Index (SPX) gained 13.06 points to 1,371.65. The Nasdaq Composite (RIXF) added 24.89 points to 3,016.11. For every stock declining roughly eight gained on the New York Stock Exchange, where nearly 90 million shares traded as of 9:50 a.m. Eastern.