Sometimes the stocks that trade on hope lead only to despair. Investors in biotech companies Amgen (AMGN) and Dendreon (DNDN) suffered serious side effects this week as the FDA raised questions about the safety and effectiveness of their flagship drugs.

Shares of Amgen plunged the most in 5 years yesterday as the future of its anemia medications came into doubt, while Dendreon shares shed nearly 70% of their value this week on concerns about its prostate cancer drug.