An investment that often is the underlying, legal structure for some exchange-traded funds. A unit investment trust purchases a fixed, unmanaged portfolio of investments according to the objectives of the trust. The trust sells shares to investors and periodically passes capital gains, dividends, and interest onto shareholders. Unit investment trusts are similar to mutual funds, however they differ because the trust doesnÂ’t actively manage the investments but a mutual fund does. Unit investment trusts have to register with the Securities and Exchange Commission under the provision of the Investment Company Act of 1940.