Exporters' Exposures to Currencies : Beyond the Loglinear Model

We extend the constant-elasticity regression that is the default choice when equities' exposure to currencies is estimated. In a proper real-option-style model for the exporters' equity exposure to the foreign exchange rate, we argue, the convexity of the relationship implies that the elasticity should depend on the exchange rate level. For instance, it should shrink to zero when the option to export becomes worthless, and that should happen at a critical exchange rate that is still strictly positive. We propose a class of tractable multi-regime regression models featuring, in line with the real-options logic, smooth transitions and within-regime dynamics in the foreign exchange exposure. We then analyze the exchange rate exposure of Chinese exporting firms and find that the model in which the moneyness of the export option has a positive impact on the exchange rate exposure detects a significantly positive and convex exposure for 40% and 65% of the firms depending on whether the market return is included in the regression or not