Autumnal trading

After enduring the terrific pounding in July, the biotech sector has to be hoping that the coup de grace has been avoided. The 9 percent drop in the BioCentury 100 Price Level in the week ended July 12 was the worst in more than three years. That was followed two weeks later by another 6 percent drubbing. But the past month of trading has shown some signs of a floor, with the BioCentury 100 and both the Carson Life Science Indexes making very modest recoveries(see B12). Now it's time to prepare for the fall session, which will reveal whether the late summer bump has generated enough momentum to push valuations up toward the new year.

Here's a look at how some of the indexes have performed over the past three fall sessions. Each period begins the day following Labor Day and ends with the day preceding Thanksgiving...