Alzheimer’s Study Lacks `Shock and Awe’ Biogen Investors Sought

An experimental Alzheimer’s disease drug from Biogen Inc. and Eisai Co. slowed the progression of the earliest stages of the devastating condition by 30 percent in a study, a first in the decades-long research that has been littered with failures.

But biotech investors were hoping for a bigger breakthrough.

Biogen shares dropped 8.4 percent to $351.49 as of 9:46 a.m. in New York after closing at the highest in three years in anticipation of the results Wednesday night. Eisai, which had been trading near all-time highs, plunged in Tokyo, and BioArctic AB, the Swedish company that originally developed the medicine, ...