Calculation of Volatility in a Jump-Diffusion Model

Abstract

A common way to incorporate discontinuities in asset returns is to add a Poisson process to a Brownian motion. The jump-diffusion process provides probability distributions that typically fit market data better than those of the simple diffusion process. To compare the performance of these models in option pricing, the total volatility of the jump-diffusion process must be used in the Black-Scholes formula. A number of authors, including Merton (1976a & b), Ball and Torous (1985), Jorion (1988), and Amin (1993), miscalculate this volatility because they do not include the effect of uncertainty over the jump size. We calculate the volatility correctly and show how this affects option prices.