Biotech Shares Slide After Genentech Shares Were Downgraded in Wake of Earnings Report

NEW YORK (AP) -- Shares of biotechnology companies are trading lower Friday, after Genentech reported lower-than-expected quarterly revenue due to disappointing sales of cancer drug Avastin. Thomas Weisel Partners analyst M. Ian Somaiya downgraded the stock to "Market Weight" from "Overweight," forecasting "tepid growth" until 2009.

Here's how shares of some biotech firms performed shortly after the market's open:

San Francisco-based Genentech Inc. slipped 55 cents to $77.45

Cambridge, Mass.-based Biogen Idec Inc fell $1.43, or 2.2 percent, to $65

Foster City, Calif.-based Gilead Sciences Inc., which has held strong in its sector due to growth in its HIV franchise, saw shares dip $1.08, or 2.1 percent, to $51.01

Thousand Oaks, Calif.-based Amgen Inc. fell 41 cents to $43.57

The sole member of the Amex Biotechnology Index bucking the downward trend was PDL BioPharma Inc., after the Redwood City, Calif.-based company said late Thursday it will spinoff its biotechnology assets into a separate company and pay shareholders a special $4.25 dividend.

Shares spiked $1.82, or 15.5 percent, to $13.53.