A hedge fund is an investment fund open to a limited range of investors that undertakes a wider range of investment and trading activities than long-only investment funds, and that, in general, pays a performance fee to its investment manager. Every hedge fund has its own investment strategy that determines the type of investments and the methods of investment it undertakes. Hedge funds, as a class, invest in a broad range of investments including shares, debt and commodities.

As the name implies, hedge funds often seek to hedge some of the risks inherent in their investments using a variety of methods, most notably short selling and derivatives. However, the term "hedge fund" has also come to be applied to certain funds that do not hedge their investments, and in particular to funds using short selling and other "hedging" methods to increase rather than reduce risk, with the expectation of increasing the return on their investment.