A company or trust that uses its capital to invest in other companies. There are two principal types: the closed-end and the open-end, or mutual fund. Shares in closed-end investment companies, some of which are listed on the New York Stock Exchange, are readily transferable in the open market and are bought and sold like other shares. Capitalization of these companies remains the same unless action is taken to change, which is seldom. Open-end funds sell their own shares to investors, stand ready to buy back their old shares, and are not listed. Open-end funds are so called because their capitalization is not fixed; they issue more shares as people want them.