Wall Street slumps as Brexit takes investors by surprise

U.S. stocks fell sharply on Friday, with the Dow Jones industrial average dropping as much as 538 points, as Britain's vote to quit the European Union sent a shock wave through global financial markets. The S&P 500 index and Dow were on track for their biggest one-day percentage drop since September, while the Nasdaq composite index was headed for its worst day since August. Global financial markets plunged and sterling sank to its lowest since 1985 after Britons voted by about 52-48 percent