NEW YORK - US stocks fell on Friday, ending four weeks of back-to-back gains, as political instability resurfaced in Europe and investors braced for a confidence vote in Greece after US markets close.The vote on Greek Prime Minister George Papandreou leaves the fate of a $130 billion bailout deal hanging in the balance. Investors are once more chewing over worst-case scenarios after markets were again engulfed by volatility less than a week after a framework solution to Greece's woes had been agreed.The problem for investors is that any result of the confidence vote is unlikely to end the uncertainty hanging over Greece and the euro zone. Instead, it will probably begin a protracted political and diplomatic process.Stock sectors most exposed to weakness in European banks and tied to economic growth, such as industrials and financials, were among the weakest. The S&P's financial index led losses, falling 1.4 percent on the day.
