Wall Street edges lower in thin trade

Investors remain on edge from Washington gridlock over fiscal cliff

US stocks edged lower on Monday after the S&P 500 suffered its worst drop since mid-November on continued worry legislators will be unable to reach a deal to avert the "fiscal cliff".

The Dow Jones Industrial Average dropped 27.95 points, or 0.21%, to 13,162.89. The Standard & Poor's 500 Index dropped 2.55 points, or 0.18%, to 1,427.60. The Nasdaq Composite Index dropped 6.23 points, or 0.21%, to 3,014.78.