Dow Jones ends day down more than 500 points on China fears

The Dow Jones industrial average has plunged more than 530 points and is in a correction amid a global sell-off sparked by fears about China's slowing economy. Oil tumbled below $40 per barrel for the first time since the financial crisis.

The Dow Jones industrial average fell to 16,459.75, and ended down 3.1 percent on Friday. The Standard & Poor's 500 index dropped 64.84 points, or 3.2 percent, to 1,970.89. The Nasdaq slid 171.45 points, or 3.5 percent, to 4,706.04.