Another miserable day on Wall Street knocked 464 points off the Dow Jones Industrial average, bringing its losses since Friday to more than 1,700 points.
The index is now down more than 10 per cent for December, putting it on track for its worst monthly loss in almost a decade.
The technology-heavy Nasdaq is now down almost 20 per cent from the peak it reached in August.
After steady gains through the spring and summer, stocks have fallen sharply in the fall as investors worry that global economic growth is cooling off.
The S&P 500 fell 39 points, or 1.6 per cent, to 2,467.
The Dow lost 464 points, or 2 per cent, to 22,859.
The Nasdaq fell 108 points, or 1.6 per cent, to 6,528.