Hedge funds are less regulated than typical retail mutual funds, and there are fewer disclosure requirements relating to the information about the fund, which must be made public. For many years, hedge funds were not required to tell anyone anything about how they invested their clients' money. However, in 2011, the rules in the US changed to require hedge fund managers to disclose at least some information to the Securities and Exchange Commission (the SEC) a US regulator about the nature of the investments they held. The lower levels of regulation allow hedge funds to do many things that a retail mutual fund cannot do. An example of this is to use leverage, which involves borrowing money to invest alongside a client's invested funds. This can magnify gains for investors, but also increases the risk of larger losses. Other investment avenues open to hedge funds, which are not available to traditional mutual funds include the ability to use derivatives freely and the ability to engage in short selling, which involves borrowing stock to then sell and profit from a hoped for subsequent fall in the stock's value. As a result of being able to use short selling and derivatives, hedge funds often try to generate positive returns where the underlying investment markets are rising or falling, and as such are sometimes referred to as absolute return funds. In contrast to more traditional funds which try to outperform a benchmark or index and are therefore referred to as relative return funds. However, the flexibility that hedge funds have to invest in this wide variety of different investment strategies does impact on who is allowed to invest in hedge funds. Although hedge funds can generate high returns, they also may take on significantly more risk and use more complex investment strategies to do so. As a result, retail investors are not allowed to invest in hedge funds. Hedge funds are only open to institutional investors, high net worth individuals and sophisticated investors. The rules on what this means, specifically differ by country to be able to invest in a hedge fund, an investor must invest a significant amount of money. Initial minimum investment amounts are set by the hedge fund itself and can range anywhere from a hundred thousand dollars to a million dollars. Finally, hedge funds tend to be much less liquid than typical mutual funds. Hedge funds can place limitations on when investors can take money outta the fund, potentially as infrequently as once per quarter, or even once per year.