Duration is a value-weighted measure of average maturity which is commonly associated with portfolios of fixed-income securities. However, the concept finds application in option pricing theory also. This article shows that if options are valued by the Black (1976) formula and a comparative-statics methodology is employed, then the interest rate sensitivity of a portfolio of European options is equal to its duration. If the options are instead valued through the Black-Scholes (1973) formula, then the interest rate sensitivity is equal to only the ‘bond-equivalent duration’ inherent in a dynamic replication strategy for the option portfolio.

This paper examines properties of daily stock returns and how the particular characteristics of these data affect event study methodologies. Daily data generally present few difficulties for event studies. Standard procedures are typically well-specified even when special daily data characteristics are ignored. However, recognition of autocorrelation in daily excess returns and changes in their variance conditional on an event can sometimes be advantageous. In addition, tests ignoring cross-sectional dependence can be well-specified and have higher power than tests which account for potential dependence.