Shares of drug maker King Pharmaceuticals Inc. rose Thursday after a Natixis Bleichroeder analyst upgraded the stock, pointing to its "astounding" low levels.

Switzerland's blue-chip index SMI dropped 4.5 percent Thursday to close below 6,000 for the first time since April 2005.

Cowen and Co. analyst Sara Michelmore downgraded shares of Gen-Probe Inc. to "Neutral" from "Outperform" Friday, saying sales of the blood-screening system Ultrio not reaching previous expectations.

Roche Holdings' $43.7 billion bid to buy the rest of Genentech highlights drugmakers' growing reliance on biotech products.

Swiss drugmaker Roche Holding offered to acquire all outstanding shares in its U.S. partner Genentech for $43.7 billion in cash to reinforce its position in cancer medicines.

Second-quarter net profit at Novartis rose 17 percent to $2.27 billion, helped by the weak U.S. dollar and cost cutting efforts, beating forecasts and boosting its shares.

A bout of risk aversion dented European stocks on Tuesday as jitters grew over potential credit-related problems at banks and inflation, while typically defensive stocks such as pharmaceuticals and food rallied.

Drug maker Novartis reported a better-than-expected rise in first-quarter profit, thanks to strong vaccine sales, while quarterly sales at Nestle also beat expectations.

Novartis has agreed to buy Nestle AG's percent stake in U.S. company Alcon in a deal worth up to $39 billion to boost its eye care business, the Swiss drugmaker said on Monday.