An undisclosed fee or sales charge, which is often hidden in the fine print of a fund's prospectus or in an insurance contract. In some cases, investors and clients do not realize they are paying the hidden load, as explicit attention is never drawn to the issue. A hidden load is a cost that a customer is typically never told about. For example, most investors are unaware of the 12b-1 fee that mutual funds often charge. With this hidden load, the investor will pay an small, annual charge to cover the fund's promotional and advertising expenses.