Behavioralizing the Black-Scholes Model

Abstract

In this article, I incorporate the anchoring-and-adjustment heuristic into the Black-Scholes option pricing framework, and show that this is equivalent to replacing the risk-free rate with a higher interest rate. I show that the price from such a behavioralized version of the Black-Scholes model generally lies within the no-arbitrage bounds when there are transaction costs. The behavioralized version explains several phenomena (implied volatility skew, countercyclical skew, skew steepening at shorter maturities, inferior zero-beta straddle return, and superior covered-call returns) which are anomalies in the traditional Black-Scholes framework. Six testable predictions of the behavioralized model are also put forward.

Keywords: Black-Scholes, Anchoring-and-Adjustment, Implied Volatility, Zero-Beta Straddle, Covered-Call, Leverage-Adjusted Return

JEL Classification: G13, G12