A big investor, whether a person or organization, who routinely purchases a large number of shares in companies and then dismisses ineffective managers to improve the value of shares. Investors like Ivan Boesky, Carl Icahn, Ronald Perelman, T. Boone Pickens used to take over companies with ailing management in the 1980s with the intention to boost their performance and consequently tap into their full business potential. Corporate raiders do so with a view to making a hostile takeover bid, i.e., they attempt to acquire a controlling interest in the voting share capital, in response to the opposition from directors or stockholders.