The S&P 500 lost 9.28 points, or 0.44 percent, to 2,088.66 and the Nasdaq Composite dropped 47.16 points, or 0.92 percent, to 5,058.41.
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 US presidential election.
The stock was the biggest drag on the S&P 500 as well as on the tech-heavy Nasdaq, which also posted its eighth straight day of losses.
