NEW YORK (MarketWatch) — U.S. stocks dropped on Wednesday, with the S&P 500 index posting its longest decline since December, as a possible government shutdown trumped better-than-forecast economic reports. “It’s been a very good year for the stock market, but people are pausing to worry about what is going on in Washington. One of the few things you can say about the stock market is it hates uncertainty,” said David Kelly, chief market strategist at J.P. Morgan Funds. The Dow industrials (DJI JIA) lost 61.33 points to 15,273.26. The S&P 500 index (SNC:SPX) shed 4.65 points to 1,692.77. The Nasdaq Composite (NASDAQ:COMP) declined 7.16 points to 3,761.10.