Unit investment trusts are more restricted in terms of how they manage their portfolios than open-ended funds. Unit investment trusts typically do not immediately reinvest dividends that may be paid or distributed to shareholders, but hold the dividends, and at some future point in time distribute these dividends to all investors. Unit investment trusts may not loan out securities that make up their portfolios, and must reproduce the index they are replicating. A unit investment trust has a specific expiration period when the trust is terminated, something an open-ended fund does not have to do. The time when a unit investment trust might terminate may be in a range of several years to several decades.