A closed end investment company is also known as a closed-end fund, a closed-end fund (CEF), a closed-end investment trust, or a closed-end mutual fund. These terms are interchangeable and refer to a type of investment company that issues a fixed number of shares, which are traded on a stock exchange like a stock. Unlike open-end funds, which continuously issue and redeem shares, closed-end funds typically do not issue new shares or redeem existing shares. This makes them less susceptible to market fluctuations, but also means they can sometimes trade at a premium or discount to their net asset value (NAV).