istolethetv via FlickrStocks are dropping again to start the week.
In early trade, the Dow was down 178 points, the S&P 500 was down 22 points, and the Nasdaq was down 38 points.
The Dow and the S&P 500 were down more than 1%.
Stocks were sliding as the price of oil continued to make new lows, with West Texas Intermediate crude falling below $51 for the first time since April 2009.
Brent crude oil, the international benchmark, was also making new lows, falling below $55 a barrel for the first time since the spring of 2009.
The decline on Monday marks the third straight day that stocks are headed for losses, with the S&P 500's slight decline on Friday marking the first time since 2008 that the benchmark index finished one year with losses and opened the next year in the red.
Meanwhile, the US dollar is rallying, with the euro falling to nine-year lows, while the dollar has exceeded parity - or equal value - with the Swiss franc.