Ebb & Flow

In its early years, the biotech sector would rise or fall on news from a single bellwether. But over the past decade, investors have become more sophisticated and understand that news from one company is not necessarily a portent for the rest of the group.

Last week, however, news that Genentech's Xolair ruMAb-E25 to treat adult allergic asthma would not be approved this year drove investors out of not only DNA and partners Tanox (TNOX) and Novartis (NVS), but out of biotech stocks in general (see Cover Story). ...