내재위험회피도에 반영된 기대와 위험선호의 이질성

The study empirically examines the anomaly patterns of implied risk aversion obtained by comparing the statistical density of KOSPI 200 index returns and the state-price density implied in KOSPI 200 index options prices and potential source of the anomaly patterns with heterogeneous beliefs as center. The anomaly patterns can be summarized as pronounced U-shaped patterns and negative values of risk aversion. The methodology of Jackwerth(2000), Aїt-Sahalia and Lo(2000)is used to infer implied risk aversion, which can estimate time-varying implied risk aversion functions across each state of underlying asset price at option’s maturity and do not need ex-ante assumptions of a complete market and the specific utility function of representative agent. The empirical results are summarized as follows. Firstly, the implied risk aversion estimates are puzzling, exhibiting pronounced U-shaped patterns and negative values. Secondly, the smile patterns of implied risk aversion functions across several estimation periods of the subjective distributions suggest that heterogeneous beliefs are likely cause of the smile. When the smile patterns caused by heterogeneous beliefs are disappeared after applying subjective distributions having short-term estimating periods, preferences of the pricing-representative agent exhibit decreasing relative risk aversion functions. According to the theory derived by Benninga and Mayshar(2000),the essence of this results is heterogeneity in investor attitudes towards risk. Lastly, because of the investors' risk preferences heterogeneity, negative values of risk aversion imply possibility of the existence of some investors who like to take risk and is even willing to pay for it.