Stock surge lacks easy explanation

By Karen Bernstein

Sometimes there's a clear cause and effect in stock price movements. But other times, the workings of the market are a mystery.

The BioCentury 100 rose 11 percent last week to 1349.22, continuing an upward swing that started nine weeks ago. The weekly combined gain for the 100 stocks matched the highest move of the past year - recorded the week after President Clinton was elected in November - and last week's volume was the third highest of the past 12 months.

In fact, the BioCentury 100 Price Level is now just 10 percent below its January high of 1504.94, when the combined influence of dismal product news and the president's attack on drug prices burst the post-election bubble and caused the index to plummet 31 percent.