The stock market had its worst drop in nearly a month as investors worried about more signs of weakness in China's economy. The Dow Jones industrial average dropped 312 points, or 1.9%, to 16,001 Monday. The Standard & Poor's 500 index sank 49 points, or 2.6%, to 1,881. The Nasdaq composite lost 142 points, or 3%, to 4,543. Biotechnology stocks, until recently a high-flying sector, continued to drop sharply.
Mining, energy, and basic materials stocks also fell hard. Tumbling prices for oil, copper, and other commodities have hurt profits at those companies. The losses were widespread, with 98% of the stocks in the S&P 500 index ending lower. Bond prices rose. The yield on the 10-year Treasury note fell to 2.10%. (Read more Dow Jones stories.)