US STOCKS-Wall Street rises in volatile session ahead of jobs data
* ECB hints at prolonging bond-buying program
* Exxon Mobil boosts S&P, Apple weighs
* Joy Global falls after slashing full-year forecast
* Indexes close mixed: Dow up 0.14 pct, S&P up 0.12 pct, Nasdaq 0.35 down pct (Updates to close, adds comment)
By Noel Randewich
Sept 3 (Reuters) - U.S. stocks ended slightly higher on Thursday as investors, on edge after recent turmoil in China's markets, looked toward a key U.S. jobs report that may figure in the Federal Reserve's decision about when to lift interest rates.
Major U.S. indices at one point rose strongly over 1 percent but relinquished those gains to dip into negative territory as worries about China's economy weighed on traders' minds, though the Dow Jones industrial average and S&P 500 managed to hold on to end modestly higher.
It was the second consecutive day of increases after over two weeks of China-driven market turmoil that has left the S&P 500 down 9 percent from its all-time high in May.
"After a waterfall decline like we had over a week ago, you can have violent moves both up and down," said Mark Luschini, chief investment strategist at Janney Montgomery Scott in Philadelphia. "That's a little of what we're seeing now as well as positioning in advance of the jobs number tomorrow." Continuación...