The S&P 500 is down about 1.7%, the Dow Jones Industrial Average is off about 1.3%, and the Nasdaq is down 2.9%. In Europe, most equity indices closed lower as well. Spain's IBEX 35 was the worst performer there, down 1.4%.

Notably, biotech stocks are selling off hard.

Some other big losers in the U.S. include Bed, Bath & Beyond (down more than 6%), Alexion Pharmaceuticals (down more than 5%), TripAdvisor (down almost 5%), and First Solar (down about 4%).

The dollar is down 0.6% against the yen, trading near ¥101.40. The dollar is down about 2.5% against the yen since the release of the March jobs report in the U.S. on Friday.

The release of weekly U.S. jobless claims figures this morning revealed that initial claims fell to the lowest level since May 2007 in the week ended April 5. Overnight, the release of Chinese trade data revealed figures on import and export growth in March that were both worse than expected.