From the Motley Fool:
"Shares of Nasdaq Biotechnology index were down more than 4% while the S&P Biotech index plunged more than 5%. Peering in to specific popular mid- and small-cap biotech stocks revealed even more carnage. However, today's big losses come on the tail of strong annual performance. As we enter a period of uncertainty with the possibility of a Lehman-like single-day market collapse, investors are paring positions in some of the market's biggest outperformers of the last 12 months and reducing their exposure to the volatile biotech sector."