We use a sample of 269 UK non-financial firms to study the sensitivity of foreign exchange exposure, and its determinants, to the different estimation methods. The standard Jorion's model suggests that 14.93% (30.50%) of the firms in our sample are exposed directly or indirectly to the fluctuations in the TWC (the US$, the Euro or the JP¥). However, the exposure increases substantially to 85.13% (96.65%) when time varying exposure regressions with orthogonalized market returns are used. We also show that the determinants of currency exposure are model-dependent. While the cross-sectional results suggest very little or no relationship between firm-specific factors and currency exposure, the explanatory power of these factors increase when data is pooled across firms and time.
JEL Classifications: F31; F23Keywords: Foreign exchange exposure; Currency risk; Panel estimation 2
IntroductionSeveral studies predict that all firms should be subject to foreign exchange exposure as their cash flows are affected, directly or indirectly, by exchange rate movements (Shapiro, 1975;Heckman, 1985;Levi, 1994;Marston, 2001). In the light of this, it is puzzling why most empirical studies show that foreign exchange fluctuations have little or no impact on stock returns (Jorion, 1990;Bartov and Bodnar, 1994;El-Masry et al. 2007;Hutson and Stevenson, 2010).This study uses a sample of 269 UK non-financial firms to investigate whether the weak empirical association between exchange rate changes and stock returns can be attributed to bad model problems. Our analysis makes three important methodological contributions to the literature on the foreign exchange exposure of individual firms. First, we relax Jorion's (1990) assumption that foreign exchange exposure is constant over time.Several studies (Smith and Stulz, 1985;Allayannis and Weston, 2001;Dunne et al., 2004) show that a firm's exposure to exchange rate movements is related to firm-specific factors, such as size, liquidity, hedging activities and growth opportunities, which are expected to vary over time. We use GARCH-based two-factor asset pricing model with time varying coefficients (GARCH-TVC hereafter) to model the time varying nature of firms' exposure to currency movements. 1 Second, Priestley and degaard (2007) argue that the exposure coefficient obtained from Jorion's model does not capture the stock's total exposure to the foreign exchange movements. Instead, it only measures the stock's exposure over and above that of the market portfolio. Priestley and degaard (2007) suggest that orthogonalized, rather than actual, market returns should be used to estimate the exchange rate exposure. We improve on Priestley and degaard's (2007) methodology by allowing the coefficients and the residuals of the orthogonalized regressions to vary over time. Finally, previous studies use cross-sectional analysis to examine the determinants of the foreign exchange exposure.Although some of these determinants, such as industry, vary only across firms, others vary across firms a...