The S&P 500 continues to make new lows in after-hours trading.
Right now, futures have fallen to levels around $1540 – down 2.6% on the day.
This is the biggest sell-off in stocks of 2013 so far, and comes after weaker than expected economic data out of China, weak housing data in the United States this morning, and of course, a massive sell-off across the commodity complex, most notably in gold (which is down 10% today).
Meanwhile, the fallout from two explosions at the finish line of the Boston Marathon this afternoon – in which two have been reported dead and dozens injured – continues to unfold.
More From Business Insider