Shares of Alexion fell Tuesday after the biopharmaceutical company said it missed its goal in a late-stage trial of the drug Solaris.
The stock ended the day down nearly 11 percent after the announcement, and has fallen more than 27 percent this year.
Alexion's drug Solaris is being studied as a treatment for a neuromuscular disease called Myasthenia Gravis, or MG, which causes patients to suffer muscle weakness that makes it difficult or impossible to perform daily activities like walking, talking, swallowing and breathing normally.
The study did not show a "statistical significance" from the baseline after week 26 of the trial, the company said. While it missed the primary goal, the study did hit targets on some secondary endpoints.