Cassava Sciences' Alzheimer's drug simufilam failed its Phase 3 trial and the stock plummeted ~90%. See why I changed my rating on SAVA to Sell from Strong Sell.

Cassava Sciences' troubled development of Alzheimer's disease candidate simufilam looks like it may have finally reached the end. The Austin, Texas-based biotech revealed that simufilam failed its first phase 3 test in mild-to-moderate Alzheimer's and a second study has now been halted, leading to an 84% drop in its share price.

The Cassava Sciences story ended Monday exactly as many knew it would — with the company’s experimental drug for Alzheimer’s disease, simufilam, failing a clinical trial.