Why Ionis Pharmaceuticals Stock Is Down 13% This Week

Why Ionis Pharmaceuticals Stock Is Down 13% This Week

Shares of Ionis Pharmaceuticals (NASDAQ: IONS), a biotechnology company, have fallen around 13.6% since their closing price on Friday, Oct. 15, 2021. Investors were disappointed by phase 3 clinical trial results for tofersen, an experimental treatment for amyotrophic lateral sclerosis. Treatment with tofersen was supposed to help reduce physical symptoms of ALS, a progressive neurodegenerative disorder that affects around 20,000 new U.S. patients annually.