"The paper also found that the longer CEOs were at the helm, the more pronounced was their firms’ poor performance. Cooper says this is because those CEOs are able to appoint more allies to their boards, and those board members are likely to go along with the bosses’ bad decisions. “For the high-pay CEOs, with high overconfidence and high tenure, the effects are just crazy,” he says. They return 22% worse in shareholder value over three years as compared to their peers."