The risks that is inherent to foreign exchange derivatives operations, centering her analysis in the “principle of foreign exchange lock”, a kind of range within which the exchange rate can vary without causing losses to either party. With such mechanism, the losses for one of the parties would happen in case the exchange rate reached and exceeded to some companies that did not expect an abrupt and accentuated depreciation of the Real, when they locked theire foreign exchange positions below 2 Reais per dollar.