Lie Symmetry Methods for Local Volatility Models
33 Pages Posted: 10 Sep 2016
Date Written: September 6, 2016
Abstract
We investigate PDEs of the form u_t = 1/2 σ^2 (t, x)u_{xx} − g(x)u which are associated with the calculation of expectations for a large class of local volatility models. We find nontrivial symmetry groups that can be used to obtain standard integral transforms of fundamental solutions of the PDE. We detail explicit computations in the separable volatility case when σ(t, x) = h(t)(α βx γx2), g = 0, corresponding to the so called Quadratic Normal Volatility Model. We also consider choices of g for which we can obtain exact fundamental solutions that are also positive and continuous probability densities.
Keywords: Lie symmetries, fundamental Solution, PDEs, Local Volatility Models, Normal Quadratic Volatility Model
JEL Classification: C6, C63, G1, G12, G13
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