The Favorite/Long-Shot Bias in S&P 500 and Ftse 100 Index Futures Options: The Return to Bets and the Cost of Insurance

Abstract

This paper examines whether the favorite/long-shot bias that has been found in gambling markets (particularly horse racing) applies to options markets. We investigate this for the S&P 500 futures, the FTSE 100 futures and the British Pound/US Dollar futures for the seventeen plus years from March 1985 to September 2002. Calls on the FTSE 100 with three months to expiration display a relationship between probabilities and average returns that are very similar to the favorite/long-shot bias in horse racing markets pointed out by Ali (1979), Snyder (1978) and Ziemba & Hausch (1986). There are slight profits from deep in-the-money calls on the S&P 500 futures and increasingly greater losses as the call options are out-of-the-money. For 3 month calls on the FTSE 100 futures, the favorite bias is not found, but a significant long-shot bias has existed for the deepest out of the money options. For call options in both markets, for the one month horizon, only a longshot bias is found. For the put options on both markets, and for both 3 month and 1 month horizons, we find evidence consistent with the hypothesis that investors tend to overpay for all put options as an expected cost of insurance. The patterns of average returns is analogous to the favorite/longshot bias in racing markets. For options on the British Pound/US Dollar, there does not appear to be any systematic favorite/long-shot bias for either calls or puts.

Keywords: long-shot bias, gambling, option prices, implied volatilities

JEL Classification: C15, G13