Greek debt fears shake US stocks
US stocks have closed broadly lower following steep declines in Europe.
Investors are worried that Greece may default on its debt and exit the euro currency union.
Chinese regulators have also been taking steps to rein in a runaway stock market.
In the US, American Express and other companies fell after releasing disappointing results.
The Dow Jones industrial average fell 279 points, or 1.5%, to 17,826. It was down as much as 357 points earlier.
The Standard & Poor's 500 index lost 23 points, or 1.1%, to 2,081.
The Nasdaq composite fell 76 points, or 1.5%, to 4,931.
European markets fell sharply. Germany's DAX lost 2.6% and traders shifted money into German government bonds, which investors see as a safe haven in turbulent times.