A sovereign wealth fund (SWF) is a government-owned enterprise that invests a portion of its country's foreign-exchange reserves in global financial markets.
These reserves consist of a balance of payments surplus, also called a current account surplus, that are created because the payments received in overseas currencies for the country's exports, such as natural resources or manufactured goods, exceed what its residents are paying for imports.
Unlike the traditional overseas investments that governments make to ensure liquidity, such as the purchase of US Treasury securities, SWF assets are separate from official reserves and are typically invested in the private sector to produce higher returns.
SWFs are controversial, in part because their investment strategies, portfolio holdings, and returns are generally secret and in part because of the concern that the sponsoring countries could exert substantial economic pressure on the companies and countries where they invest.