The Dow Jones industrial average has suffered its biggest plunge of the year.
The 334-point drop came a day after the Dow saw its biggest gain of the year.
The Dow has not had this many big swings since August 2011, when the US government lost its AAA credit rating.
Energy stocks led the slide as the price of oil continued to slump. Oil fell 2% on worries that the global economy will slow even as production remains high. Chevron fell 3%.
At the closing bell the Dow was down nearly 2% at 16,659.
The Standard and Poor’s 500 fell 40 points, or 2.1%t, to 1,928. The Nasdaq composite fell 90 points, or 2%, to 4,378.