Clearly Irrational Financial Market Behavior: Evidence from the Early Exercise of Exchange Traded Stock Options
61 Pages Posted: 21 Aug 2001
Date Written: August 2001
This paper analyzes the early exercise of Chicago Board Options Exchange listed calls by different classes of investors over the 1996-1999 period. We present two main findings. First, there are a large number of early exercises that can be identified as clearly irrational without invoking any model of market equilibrium, and these exercises are not uniformly distributed across the investor classes. Customers of discount brokers and customers of full service brokers both engage in a significant number of irrational exercises while traders at large investment houses exhibit no irrational early exercise behavior. Second, irrational exercise is triggered both by the underlying stock price attaining its highest level over the past year and by the underlying stock having high past returns. Our findings provide evidence that prospect theory is operative in the options market and that it applies differentially across various classes of investors.
Keywords: Market Efficiency, Behavioral Finance, Early Exercise, Irrational Behavior, Prospect Theory
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