Managerial Discretion and the Economic Determinants of the Disclosed Volatility Parameter for Valuing ESOs
This study investigates the determinants of the expected stock-price volatility assumption that firms use in estimating ESO values and thus option expense. We find that, consistent with the guidance of FAS 123, firms use both historical and implied volatility in deriving the expected volatility parameter. We also find, however, that the importance of each of the two variables in explaining disclosed volatility relates inversely to their values, which results in a reduction in expected volatility and thus option value.