Using a large dataset of hand-collected information on activist interventions from 2008 to 2014, we examine why certain hedge funds succeed in the face of competition. We document that the top hedge funds succeed, not merely because of how they select targets, but because they acquire a reputation for what we label “clout and expertise.” These hedge funds do not intervene more frequently; to the contrary, activists with more interventions are associated with lower returns. Instead, top activists have a demonstrated ability to succeed in difficult interventions by targeting large firms, launching successful proxy fights, filing and winning lawsuits, pressuring target boards through the media, overcoming anti-takeover defenses, and replacing board members. These activists' successes appear to result more from board representation, improved performance, and monitoring management than from capital structure or dividend policy changes. •Top activists have a reputation for what we label “clout and expertise.”•Top activists have an ability to succeed in difficult interventions by targeting large firms.•Top activists launch successful proxy fights, and file and win lawsuits.•Top activists overcome anti-takeover defenses, and replace board members.•Top activists successes appear to result from board representation and monitoring management.