Wall Street has suffered its largest selloff in 10 months after Britain's decision to leave the European Union. In the busiest trading volume for a single session in nearly five years, financial stocks led the decline on the S&P 500 with a 5.4% decline - the largest for the sector since November 2011. The S&P 500 lost all the year's gains and suffered its largest decline since late August last year. Meanwhile the Dow Jones dropped 611 points, with both it and the S&P finishing about 3.5% lower. Many expect the next weeks to remain volatile.