U.S. stocks posted their largest percentage drop since April 2009 on Thursday, with all three major indexes ending down more than 3 percent.

Indexes earlier in the afternoon had plunged even more steeply, before paring losses.

The Dow Jones industrial average was down 347.80 points, or 3.20 percent, at 10,520.32. The Standard & Poor's 500 Index was down 37.75 points, or 3.24 percent, at 1,128.15. The Nasdaq Composite Index was down 82.65 points, or 3.44 percent, at 2,319.64.

(Reporting by Angela Moon, Editing by Leslie Adler)