U.S. stocks joined a selloff in global equities, while currencies of commodity-producing nations tumbled as fresh signs of weakness in China's economy rekindled concern that a slowdown there could spread.

The Standard & Poor's 500 Index fell for the fourth time in five days as crude extended losses at a six-year low. Emerging-market shares also declined as a slump in Chinese trade intensified concern over the scope of the economy's weakness. Iron ore fell to an historic low. Oil's slide drove a rally in long-term government bonds from the U.S. to Germany one week before the Federal Reserve is predicted to raise interest rates.

Chinese exports fell for a firth month, while imports capped a record 13th month of declines in November, rekindling concerns over Asia's largest economy akin to those that precipitated the summer rout on global financial markets. Oil's selloff is clouding the prospects for recoveries in the U.S. and Europe as capital spending wanes and inflation holds below central-bank targets, with the Fed poised to raise rates for the first time in a decade at its meeting next week.

The S&P 500 fell 0.7 percent to 2,063.59 as of 4 p.m. in New York. The index has lost 0.8 percent in December, with its only gain in the month a 2.1 percent rally on Friday. The S&P 500 is still up 10 percent from its August trough, as worries about weakness in China abated after the government took steps to boost growth and support the stock market.

Industrial companies led declines Tuesday, with Caterpillar Inc. and Boeing Co. down at least 2.3 percent. Freeport-McMoRan Inc. slid 6.8 percent to pace a drop in materials producers.

Canada's S&P/TSX Index dropped 0.9 percent to close at a two-year low, while miners led the Stoxx Europe 600 Index down 1.8 percent. Anglo American Plc plummeted 12 percent after suspending dividends for the second half of 2015 and next year. BHP Billiton Ltd. retreated 5.5 percent in London and Rio Tinto Group lost 8.4 percent.

MSCI's Asia-Pacific gauge slid 1.3 percent Tuesday as a gauge of Asian energy shares retreated 3.9 percent to the lowest level since Oct. 1. Japan's Topix index dropped 1 percent, while Australia's S&P/ASX 200 Index fell 0.9 percent, with sub-indexes of energy and raw-materials producers sliding at least 3.4 percent.