A stock fund, or equity fund, is a fund that invests in stocks, also called equity securities. Stock funds can be contrasted with bond funds and money funds. Fund assets are typically mainly in stock, with some amount of cash, which is generally quite small, as opposed to bonds, notes, or other securities. This may be a mutual fund or exchange-traded fund. The objective of an equity fund is long-term growth through capital gains, although historically dividends have also been an important source of total return. Specific equity funds may focus on a certain sector of the market or may be geared toward a certain level of risk.

Stock funds can be distinguished by several properties. Funds may have a specific style, for example, value or growth. Funds may invest in solely the securities from one country, or from many countries. Funds may focus on some size of company, that is, small-cap, large-cap, et cetera. Funds which involve some component of stock picking are said to be actively managed, whereas index funds try as well as possible to mirror specific stock market indices.