L3

Heston PDE Derivation

Quant Researcher · Stochastic Calculus

Question

Derive the Heston PDE from the multidimensional Itô lemma applied to V(t,S,ν)V(t, S, \nu) where dS=νSdW1dS = \sqrt{\nu}\,S\,dW^1 and dν=κ(νˉν)dt+ξνdW2d\nu = \kappa(\bar{\nu} - \nu)\,dt + \xi\sqrt{\nu}\,dW^2, with dW1,W2=ρdtd\langle W^1, W^2 \rangle = \rho\,dt. Identify the cross-derivative term and explain its role in generating the implied vol skew.