Closed-end investment funds are a corner of the securities world of which many investors are unaware. A closed-end fund is essentially the same as a mutual fund except no new money can enter the fund after the initial offering. Shares trade on a regulated exchange at prices more or less in line with the value of the securities held in the fund. Closed-end funds are as varied as the managers that operate them. Some specialize in income-producing securities, others in foreign stocks and bonds, while still others specialize in options-related strategies.