Pricing perpetual put options by the Black-Scholes equation with a nonlinear volatility function

We investigate qualitative and quantitative behavior of a solution to the problem of pricing American style of perpetual put options. We assume the option price is a solution to a stationary generalized Black-Scholes equation in which the volatility may depend on the second derivative of the option...

Full description

Bibliographic Details
Main Author: Grossinho, Maria do Rosário (author)
Other Authors: Kord, Yaser Faghan (author), Ševčovič, Daniel (author)
Format: workingPaper
Language:eng
Published: 2018
Subjects:
Online Access:http://hdl.handle.net/10400.5/16343
Country:Portugal
Oai:oai:www.repository.utl.pt:10400.5/16343
Description
Summary:We investigate qualitative and quantitative behavior of a solution to the problem of pricing American style of perpetual put options. We assume the option price is a solution to a stationary generalized Black-Scholes equation in which the volatility may depend on the second derivative of the option price itself. We prove existence and uniqueness of a solution to the free boundary problem. We derive a single implicit equation for the free boundary position and the closed form formula for the option price. It is a generalization of the well-known explicit closed form solution derived by Merton for the case of a constant volatility. We also present results of numerical computations of the free boundary position, option price and their dependence on model parameters.