By Olivia Goldhill Nov. 9, 2021 Reprints A vendor bags psilocybin mushrooms at a pop-up cannabis market in Los Angeles.RICHARD VOGEL/AP Eagerly awaited results of the largest-ever study of psilocybin were announced Tuesday, with Compass Pathways revealing the psychedelic drug was highly efficacious as a therapy for treatment-resistant depression. Still, the company’s stock price dropped 16.4% by the close of...