Biotech shares have suffered worse weeks based on the sector's own letdowns, but the downdraft of the overall market last week still produced a tie for the fourth largest decline in the BioCentury 100 over the past two years. With 85 of the 100 stocks in the declining category, the BioCentury index was off 5 percent last week. There have been two 6 percent sell-offs this year, plus another 5 percent downturn, all paling in comparision to the hosings of 9 percent and 10 percent in the weeks ended June 21 and July 12 of 1996, respectively.

After sliding 7 percent on Monday, the three major market indexes found a floor and rebounded somewhat by week's end. But as measured by The Carson Group's basket of 293 companies, Monday's bloodbath resulted in a biotech advance-to-decline ratio of 5-to-288. The winners included Progenitor (PGEN, up 5 percent to $4.375), Cortecs (DLVRY, up 4 percent to $14.24), Neurobiological Technologies (NTII, up 3 percent to $2.97), GalaGen (GGEN, up 3 percent to $2.0625) and Hycor (HYBD, up 3 percent to $2.25).