Option pricing bounds with standard risk aversion preferences

Abstract

For a theoretical valuation of a financial option, various models have been proposed that require specific hypotheses regarding both the stochastic process driving the price behaviour of the underlying security and market efficiency. When some of these assumptions are removed, we obtain an uncertainty interval for the option price. Up to now, the most restrictive intervals for option prices have been obtained using the decreasing absolute risk aversion (DARA) rule in a state-preference approach. Precautionary saving entails the concept of prudence; in particular, decreasing absolute prudence is a necessary and sufficient condition that guarantees that the saving of wealthier people is less sensitive to the risk associated to future incomes. If this condition is coupled with the DARA assumption we obtain standard risk aversion (SRA), which guarantees on the one hand that introducing a zero-mean background risk to wealth makes people less willing to accept another independent risk and on the other hand that an increase in the risk of the returns distribution of an asset reduces the demand for this asset. The main idea of this contribution is to apply decreasing absolute prudence and SRA rules in a state-preference context in order to obtain efficient bounds for the value of European-style options portfolio strategies. Lower and upper bounds for the options portfolio value are obtained by solving non-linear optimization problems. The numerical experiments carried out show the efficiency of the technique proposed.