US stocks dive as oil price falls back below $30
(Closed) Wall Street stocks ended the week with a sharp fall, as the price of oil dropped back below $30 a barrel.
The S&P 500 index had its worst close since August 2014, ending 41.56 points down to 1,880.28.
The losses wiped out the gains recorded on Thursday, when a small rebound in the oil price had sparked a recovery.
New US economic data showing a decline in industrial production and lower than expected holiday sales figures also shook the markets.
Energy stocks saw big falls as the price of oil fell to fresh 12-year lows.
Oil giant Chevron was one of the biggest losers on the Dow, dropping 2%.
Shares in Intel fell more than 9% after the tech giant's fourth quarter results - released late on Thursday - failed to impress investors.
Citigroup shares were down 6.4% despite the bank reporting a big increase in fourth quarter profits, helped by a fall in legal fees. The bank's exposure to the energy sector spooked some investors.