US stocks tumble as investors refocus on economy

Wall Street has ended a turbulent week with another astonishing show of volatility, plunging, recovering and then plunging again as investors absorbed another wave of downbeat economic news.

Hedge fund selling in advance of a Saturday deadline contributed to the market’s gyrations, which left the Dow Jones industrials down 337 points, or 3.82%, at the 8,497 level. The broader Standard & Poor’s 500 index fell more than 4%.