This study provides descriptive evidence on how firms respond to activist short seller reports and how these responses are associated with outcomes for the targeted firms. We show that the frequency of these reports has grown substantially in recent years. Although we find that firms respond only 31% of the time, this rate increases substantially when the report is accompanied by significantly negative abnormal returns and when the report contains new evidence. Not responding is associated with a less negative stock price response at report release and fewer adverse outcomes. Firms that launch internal investigations following the report release have significantly higher subsequent rates of stock exchange delisting and SEC enforcement actions, and lower rates of being acquired. Overall, our results highlight the impact of activist short sellers on target firms and that firm responses are associated with material outcomes.