Hedge funds and private equity increasingly play an important role in the financial services industry and corporate governance in Europe and the United States. Activist hedge funds and private equity firms have developed similar investment strategies that are designed to influence the corporate governance and organisational structure of publicly listed companies. A large number of hedge funds, for example, have adopted an investment strategy to accumulate large positions in publicly listed companies, using their ownership positions to engage in monitoring of management. Activist hedge funds often make direct interventions in the corporate governance of target firms, confronting management teams by demanding specific actions, such as changes in management, company capital structure, dividend policy and company strategy, in order to increase shareholder value. The investment strategy of private equity buyout funds is to target publicly listed companies which they can take private for a period of restructuring and governance changes. Eventually, the firm will either be returned as a publicly listed company or be sold to a strategic buyer or another investor. Activist hedge funds and private equity firms have recently come under scrutiny by regulators who are concerned about the effect of the strategies used by these funds on the companies in which they invest and the capital markets in which they operate. Existing accounts focus on the mechanisms in corporate law, taxation and labour law to address current practices of hedge fund and private equity firm managers. We examine the circumstances where direct government regulation could be supplemented with a mix of self-regulatory and co-regulatory strategies. We conclude by analysing the various regulatory responses to the propensity of activist hedge funds and private equity firms to act in concert and assess whether the reforms will have practical significance.