“The Biggest Biotech Bombshell in Years,” declared The Motley Fool of Biogen’s market-moving announcement October 22 that it was planning to file for FDA approval of the Alzheimer’s disease (AD) candidate aducanumab, being co-developed with Eisai, despite halting two failed Phase III studies of the drug in March. Investors flocked to Biogen stock, sending the company’s stock price surging 40% before the start of trading that day. When the market closed, Biogen shares finished the day 26% higher at $281.87.