The Dow Jones industrial average dropped 312 points, or 1.9 percent, to 16,001 Monday.
The Standard & Poor's 500 index sank 49 points, or 2.6 percent, to 1,881. The Nasdaq composite lost 142 points, or 3 percent, to 4,543.
Biotechnology stocks, until recently a high-flying sector, continued to drop sharply.