Unit investment trusts are one of three investment company types. A unit investment trust issues redeemable shares or units, and may buy back those shares at their approximate net asset value. Unit investment trusts typically make a one-time public offering of a specific number of shares. As opposed to a mutual fund that may continue well into the future, a unit investment trust will have a termination date established when it is created that indicates when the entire fund will terminate. For a unit investment trust that invests primarily in bonds, the termination date may be when the bonds mature. After a unit investment trust terminates, all remaining securities and positions in the portfolio are sold at the current market value, and all the proceeds are paid to investors (less any service charges or loads) at the time of sale.