This study provides new evidence on the impact of activist hedge funds in influencing target companies’ operational performances, especially distinguishing four different types of activism demands: 1) changing corporate governance, 2) restructuring balance sheet, 3) implementing growth strategies, and 4) cutting cost and divesting non-core assets. While a general improvement in operating performances is observed across activist-targeted public companies, I find that the group four hedge funds tend to have greater positive impacts as measured by operating metrics such as return on assets (ROA) and gross profit margin (GPM). The research addresses understudied areas of shareholder activism and identifies the subtle differences among different types of activist hedge funds. This analysis aims to provide passive investors a better forecast of the impact of the identified activist investor type.