Optimal hedging under departures from the cost-of-carry valuation: evidence from the Spanish stock index futures market

We provide an analytical discussion of the optimal hedge ratio under discrepancies between the futures market price and its theoretical valuation according to the cost-of-carry model. Assuming a geometric Brownian motion for spot prices, we model mispricing as a speci…c noise component in the dynamics of futures market prices. Empirical evidence on the model is provided for the Spanish stock index futures. Ex-ante simulations with actual data reveal that hedge ratios that take into account the estimated, time-varying, correlation between the common and specific disturbances, lead to using a lower number of futures contracts than under a systematic unit ratio, without generally losing hedging e¤ectiveness, while reducing transaction costs and capital requirements. Besides, the reduction in the number of contracts can be substantial over some periods. Finally, a meanvariance expected utility function suggests that the economic benefits from an optimal hedge are substantial.