An investment company that offers a fixed, unmanaged portfolio, generally of stocks and bonds, as redeemable "units" to investors for a specific period of time. It is designed to provide capital appreciation and/or dividend income.

Unit investment trusts are one of three types of investment companies; the other two are mutual funds and closed-end funds

Each unit typically costs $1,000 and is sold to investors by brokers. UITs can be resold in the secondary market. A UIT may be either a regulated investment corporation (RIC) or a grantor trust. The former is a corporation in which the investors are joint owners; the latter grants investors proportional ownership in the UIT's underlying securities.