Résumé en anglais

This note provides an example of an optimal banking panic. We construct a model in which a banking panic is triggered by the banker, not the depositors. When the banker receives a pessimistic information on the return on the bank's assets, he liquidates them prematurely in order to protect his capital. In the face of this liquidation, all depositors withdraw their funds prematurely. The premature liquidation of the bank's assets strengthens the bank's balance sheet. As a result, the banking panic does not cause bank failure and the government should not try to prevent the panic. Such a panic occured in 1857 in the United States.