Wall St. tumbles; S&P, Dow down 10 percent for the year

All 10 S&P major sectors were in the red, led by financials, especially banks. The financial sector , already the worst performing S&P sector this year, dropped 2.71 percent. Federal Reserve Chair Janet Yellen stuck to her guns on her return to Capitol Hill on Thursday, saying a weakened global economy and steep slide in U.S. equity markets is tightening financial conditions faster than the Fed wants.