In which ∆e is the variation in the exchange rate, measured in percentage points. The model does not cover quantity risk, in which the quantity of foreign currency exposure is uncertain due to the fact that the firm sells its product abroad, but it does not know how much it will sell or even at what price. So the model has some serious limitations: there is no competition or uncertainty, which leads to very stylized assessments of risk exposure. As a result, it does not have a great prediction capability, losing its value as a reference to companies planning their hedges. However, we can surpass these drawbacks by using this model not as a predictor, but an ex-post check if the effective hedge was successful or not. Following this rationale we use the ex-post EBIT as the main measure for the determination of the hedge ratio. We are concerned not with the company‟s best strategy, but with a rational hedging choice by the company‟s managers. If we can show, by using a sensitive analysis and verifying whether the type of hedge was appropriate, that the strategy used by the company was not adequate, it is not necessary to extend the model to a more comprehensive one.