U.S. stocks opened sharply higher on Thursday following a string of stronger-than-expected quarterly corporate profits, a broker upgrade for General Electric Co and fresh signs that the economic slump is waning. ExxonMobil Corp reported second-quarter results that fell short of Wall Street expectations, as natural gas and crude oil prices slid from a year ago and the global recession hurt demand for fuel. The world's largest publicly traded oil company reported adjusted quarterly earnings of 84 cents a share versus the average estimate of analysts surveyed by Thomson Reuters of $1.02 per share. Shares fell 2.1 percent to $69.90 in premarket trade. S&P 500 futures rose 8.90 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures climbed 65 points, and Nasdaq 100 futures were 14.25 points higher. The world's second-largest credit card network reported second-quarter adjusted earnings of $2.67 per share, above the average estimate of analysts surveyed by Thomson Reuters of $2.42 per share. Shares rose 6.7 percent to $201.24 in premarket trade.