Pricing Options on Mean Reverting Underliers

Abstract

For mean reverting base probabilities option pricing models are developed using an explicit measure change induced by the selection of a terminal time and a terminal random variable. The models employed are the square root process and an OU equation driven by centered variance gamma shocks. VIX options are calibrated using the square root process. The OU equation driven by centered variance gamma shocks is applied in pricing options on the ratio of the stock price for J. P. Morgan Chase (JPM) to the Exchange Traded Fund (ETF) for the financial sector with ticker XLF. For the purposes of calibrating the ratio option pricing model to market data, we indirectly infer the prices for stock options on JPM from the prices for options on the ratio, by hedging the conditional value of JPM options given XLF, using options on XLF. The implied volatilities for the options on the ratio are then indirectly observed to be fairly flat. This suggests that for JPM, the use XLF as a benchmark is a possibly good choice. It is shown to perform better than the use of the S&P 500 index (SPX). Furthermore, though the use of an unrelated stock price like Johnson and Johnson (JNJ) as a benchmark for JPM provides as good a fit as does the use of XLF, this comes at the cost of requiring a considerable smile for the implied volatilities on the ratio options and hence a more complex model for the implied distribution on the ratio.