A "closed-end fund," legally known as a "closed-end company," is one of three basic types of investment company. The two other basic types of investment companies are mutual funds (open-end investment companies) and Unit Investments Trusts (UITs).

Here are some of the traditional and distinguishing characteristics of closed-end funds:

- Closed-end funds generally do not continuously offer their shares for sale. Rather, they sell a fixed number of shares at one time (in an initial public offering), after which the shares typically trade on a secondary market, such as the New York Stock Exchange or the NASDAQ Stock Market.
- The price of closed-end fund shares that trade on a secondary market after the fund’s initial public offering is determined by market forces of supply and demand and may be greater or less than the shares’ net asset value (NAV).
- Closed-end fund shares generally are not redeemable. That is, a closed-end fund is not required to buy its shares back from investors upon request. Some closed-end funds, commonly referred to as interval funds, offer to repurchase their shares at specified intervals.
- The investment portfolios of closed-end funds generally are managed by separate entities known as "investment advisers" that are registered with the SEC.

Closed-end funds come in many varieties. They can have different investment objectives, strategies, and investment portfolios. They also can be subject to different risks, volatility, and fees and expenses.