U.S. stocks opened higher on Wednesday, following stronger-than-expected earnings results from Alcoa Inc. (NYSE: AA). Shares of aluminum producer Alcoa gained 4.55 percent to $13.10 in early trading after the company kicked-off the spring earnings season by posting first-quarter EPS of 9 cents per share, excluding items, 4 cents above Wall Street estimates, as revenue came in at $5.45 billion, compared to expectations of $5.55 billion.