A quantum model for the overpriced put puzzle
摘要
Put options are known to be priced unusually high in the market, which we refer to as the overpriced put puzzle. This study proposes a quantum model (QM) that can explain such high put option prices as fair prices. Starting from a stochastic differential equation of stock returns, we convert the Fokker–Planck equation into the Schrödinger equation. To model the market force that always draws excess returns back to equilibrium, we specify a diffusion process corresponding to a QM with a delta potential. The results demonstrate that stock returns follow a Laplace distribution and exhibit power law in the tail. We then construct a closed-form solution for European put option pricing, determining that our model better explains the returns of the S&P 500 index and its corresponding put option prices than do geometric Brownian motion-based models. This study has significant implications for investors and risk managers, presenting a model that can potentially improve derivative pricing. Future studies can generalize the model assumptions by introducing asymmetric potential drawing back excess returns to equilibrium.