J. Hull, A. White: Optimal Delta Hedging for Options

May 24, 2017

As has been pointed out by a number of researchers, the normally calculated delta does not minimize the variance of changes in the value of a trader’s position. This is because there is a non-zero correlation between movements in the price of the underlying asset and movements in the asset’s volatility. The minimum variance delta takes account of both price changes and the expected change in volatility conditional on a price change.