Pension-fund activism is the proactive use of the economic clout held by pension funds to materially improve working conditions and the conduct of corporations on behalf of unions and the pension's contributors. Pension funds are responsible for providing retirement income for employees in both the private and public sectors in some countries. The four largest are based in the United States, Australia, Japan, and Norway, respectively. In the United States, pension funds control some 10-15% of the American securities market.