S&P 500 falls for eighth straight session

NEW YORK (Reuters) - The S&P 500 fell for an eighth straight session on Thursday, its longest losing streak since the 2008 financial crisis, as Facebook shares weighed and investors grappled with uncertainty over next week's U.S. presidential election. The Dow Jones industrial average fell 28.49 points, or 0.16 percent, to 17,931.15, the S&P 500 lost 9.25 points, or 0.44 percent, to 2,088.69 and the Nasdaq Composite dropped 47.16 points, or 0.92 percent, to 5,058.41. (Reporting by Chuck