Hedging with a correlated asset: Solution of a nonlinear pricing PDE

  • Authors:
  • H. Windcliff;J. Wang;P. A. Forsyth;K. R. Vetzal

  • Affiliations:
  • Equity Trading Lab, Morgan Stanley, 1585 Broadway, New York, NY 10036, USA;School of Computer Science, University of Waterloo, Waterloo, Ont., Canada N2L 3G1;School of Computer Science, University of Waterloo, Waterloo, Ont., Canada N2L 3G1;Centre for Advanced Studies in Finance, University of Waterloo, Waterloo, Ont., Canada N2L 3G1

  • Venue:
  • Journal of Computational and Applied Mathematics
  • Year:
  • 2007

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Abstract

Hedging a contingent claim with an asset which is not perfectly correlated with the underlying asset results in unhedgeable residual risk. Even if the residual risk is considered diversifiable, the option writer is faced with the problem of uncertainty in the estimation of the drift rates of the underlying and the hedging instrument. If the residual risk is not considered diversifiable, then this risk can be priced using an actuarial standard deviation principle in infinitesimal time. In both cases, these models result in the same nonlinear partial differential equation (PDE). A fully implicit, monotone discretization method is developed for solution of this pricing PDE. This method is shown to converge to the viscosity solution. Certain grid conditions are required to guarantee monotonicity. An algorithm is derived which, given an initial grid, inserts a finite number of nodes in the grid to ensure that the monotonicity condition is satisfied. At each timestep, the nonlinear discretized algebraic equations are solved using an iterative algorithm, which is shown to be globally convergent. Monte Carlo hedging examples are given to illustrate the profit and loss distribution at the expiry of the option.