The cooperation of investors in achieving identical investment objectives, both formally and informally. This can take place, for example, in a takeover in which a group of investors cooperate. There is often a notification obligation to the regulator, depending on the regulations in the country or market in question. In the Netherlands, there are rules regarding cooperation between activist shareholders who jointly pursue a voting policy to influence the policy of a company. In some cases, however, 'acting in concert' is prohibited, such as in the case of price manipulation.