A bank run (also known as a run on the bank) is a type of financial crisis. It is a panic which occurs when a large number of customers of a bank withraw their deposits because they fear it is, or might become, insolvent. This action can destabilize the bank to the point where it becomes insolvent. Banks retain only a fraction of their deposits as cash (see fractional-reserve banking): the remainder is invested in securities and loans. No bank has enough reserves on hand to cope with more than the fraction of deposits being taken out at once. As a result, the bank faces bankruptcy, and will 'call in' the loans it has offered. This can cause the bank's debtors to face bankruptcy themselves, if the loan is invested in a plant or other items that cannot easily be sold.