U.S. stocks fell sharply on Monday, with the S&P 500 extending losses into a fourth session, as energy companies took it on the chin as the price of oil fell to its lowest since April 2009.
"It looks like the market is largely moving down in conjunction with oil prices, and there's still some fear out there on top it about about Greece possibly exiting the euro zone, and concern about Europe continuing to struggle," said Matthew Kaufler, portfolio manager at Federated Investors.
Exxon Mobil, Chevron and other oil producers fell with the price of crude, which closed just above $50 a barrel after a short visit below the psychological level during the session.
The CBOE Volatility Index, a measure of investor uncertainty, rose 12 percent to 19.92.
In Greece, Prime Minister Antonis Samaras said the current election campaign could result in a departure from the European Union should the Syriza party win, with the comments helping push the euro to a near nine-year low.
Equities did not get any relief as U.S. automakers reported strong domestic sales in December, with General Motors surpassing estimates and posting a 19 percent gain for the month.
Major U.S. Indexes
After a 350-point fall, the Dow Jones Industrial Average shed 331.34 points, or 1.9 percent, to 17,501.65, with Caterpillar and Chevron leading blue-chip declines that included 28 of its 30 components.
While the Dow is down triple digits, "we're also recently at new highs, so to have a pullback after having some pretty strong performance in December is not out of the ordinary and shouldn't scare people," Kaufler said.
The Dow last closed at a record high 18,053.71 on Dec. 26; the S&P 500 finished at a record 2,090.57 three days later.
On Monday, the declined 37.62 points, or 1.8 percent, to 2,020.58, with energy hardest hit and all 10 of its major sectors losing ground.
The Nasdaq dropped 74.24 points, or 1.6 percent, to 4,652.57.
For every share rising, more than three slid on the New York Stock Exchange, where almost 845 million shares traded. Composite volume approached 3.8 billion.
"We're starting a new year with a bit of trepidation; it's difficult for equities to get any traction when one of the asset classes is in a free fall," said Art Hogan, chief market strategist at Wunderlich Securities, referring to crude's ongoing decline.
"Clearly we haven't found a bottom in the commodity," added Hogan.
On the New York Mercantile Exchange, U.S. light crude, also known as West Texas Intermediate, briefly fell as low as $49.95, before ending at $50.04 a barrel, down $2.65, or 5 percent.
The U.S. dollar gained against the currencies of major U.S. trading partners and the yield on the 10-year Treasury note used to figure mortgage rates and other consumer loans dropped 8 basis points to 2.0356 percent.
On Friday, stocks were little moved to end Wall Street's first session of 2015.
Coming Up This Week:
Tuesday
10 a.m.: ISM nonmanufacturing for December
10 a.m.: Factory orders for November
Wednesday
8:15 a.m.: ADP employment for December
8:30 a.m.: Trade deficit for November
2 p.m.: FOMC minutes
Thursday
8:30 a.m.: Weekly jobless claims
3 p.m.: Consumer credit for November
Friday
8:30 a.m.: Nonfarm payrolls for December
8:30 a.m.: Unemployment rate
10 a.m.: Wholesale inventories for November
More From CNBC.com: