Adaptive θ-methods for pricing American options

  • Authors:
  • Abdul Q. M. Khaliq;David A. Voss;Kamran Kazmi

  • Affiliations:
  • Department of Mathematical Sciences, Middle Tennessee State University, Murfreesboro, TN 37132, United States;Department of Mathematics, Western Illinois University, 1 University Circle, Macomb, IL 61455, United States;Department of Mathematics, University of Iowa, Iowa City, IA 52240, United States

  • Venue:
  • Journal of Computational and Applied Mathematics
  • Year:
  • 2008

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Abstract

We develop adaptive @q-methods for solving the Black-Scholes PDE for American options. By adding a small, continuous term, the Black-Scholes PDE becomes an advection-diffusion-reaction equation on a fixed spatial domain. Standard implementation of @q-methods would require a Newton-type iterative procedure at each time step thereby increasing the computational complexity of the methods. Our linearly implicit approach avoids such complications. We establish a general framework under which @q-methods satisfy a discrete version of the positivity constraint characteristic of American options, and numerically demonstrate the sensitivity of the constraint. The positivity results are established for the single-asset and independent two-asset models. In addition, we have incorporated and analyzed an adaptive time-step control strategy to increase the computational efficiency. Numerical experiments are presented for one- and two-asset American options, using adaptive exponential splitting for two-asset problems. The approach is compared with an iterative solution of the two-asset problem in terms of computational efficiency.