Stocks on Wall Street end sharply lower
(Close): US shares fell sharply on Friday as the continued fall in oil prices continued to sap investors' confidence.
The Dow Jones ended down 309 points, or 1.8%, at 17,265 points.
Oil prices hit fresh seven-year lows after the International Energy Agency said growth in demand was set to slow.
Brent crude fell $1.80, or 4.5%, to $37.93 a barrel in London - a level last seen amid the 2008 global financial crisis.
US crude dropped $1.14, or 3.1%, to $35.62 - the lowest level since February 2009.
US oil has shed nearly 11% in the past week and Brent almost 12%.
Shares in US chemical firms Dow and DuPont were both lower after the two firms announced plans for a merger in deal which values the tie-up at $130bn.