An individual or group that purchases large numbers of a public company's shares and/or tries to obtain seats on the company's board with the goal of effecting a major change in the company. A company can become a target for activist investors if it is mismanaged, has excessive costs, could be run more profitably as a private company or has another problem that the activist investor believes it can fix to make the company more valuable. Activist investors aim to make money by buying shares of companies and then pushing them to change their strategy. This can include raising their dividend, launching a share buyback, spinning off a division, or an outright sale of company.