Biogen resurrects failed Alzheimer's treatment
Biogen's stock soared Tuesday. Photo: Dominick Reuter/AFP via Getty Images
Why it matters: This is a major and unexpected development that hints at a possible Alzheimer's treatment, driving Biogen's stock price up by more than 25%. But there remains widespread skepticism about how Biogen is interpreting the clinical trial data, and whether the data shows the drug is effective.