We estimate the exchange-rate exposure of the firms in our sample using model
1. We estimate each firm’s exposure in our 1993 sample using monthly return data
during the three years surrounding 1993 (1992–94). This is appropriate, since we
want to measure the contemporaneous impact of foreign currency derivatives on a
firm’s exchange-rate exposure. However, we also use a longer time interval (five
years) to estimate exposures between 1991 and 1995. Finally, we use monthly data
instead of daily or weekly, since daily and weekly exchange rate indices are noisier
and usually suffer from non synchroneity problems (nonalignment of stock-return and
exchange-rate series).
In the second stage, we examine the potential impact of a firm’s currency derivative
use on its exchange-rate exposure. Exchange-rate exposure is simultaneously
determined by a firm’s real operations (which we proxy through foreign sales) and its
financial hedging. Therefore, we include both factors in the cross-sectional regression
equation shown below: