Log-Normal Stochastic Volatility Model: Affine Decomposition of Moment Generating Function and Pricing of Vanilla Options

76 Pages Posted: 11 Nov 2014 Last revised: 15 Mar 2016

See all articles by Artur Sepp

Artur Sepp

Sygnum Bank's Asset Management

Date Written: March 7, 2016

Abstract

While empirical studies have established that the log-normal stochastic volatility (SV) model is superior to its alternatives, the model does not allow for the analytical solutions available for affine models. To circumvent this, we show that the joint moment generating function (MGF) of the log-price and the quadratic variance (QV) under the log-normal SV model can be decomposed into a leading term, which is given by an exponential-affine form, and a residual term, whose estimate depends on the higher order moments of the volatility process. We prove that the second-order leading term is theoretically consistent with the expected values and covariance matrix of the log-price and the quadratic variance. We further extend this approach to the log-normal SV model with jumps. We use Fourier inversion techniques to value vanilla options on the equity and the QV and, by comparison to Monte Carlo simulations, we show that the second-order leading term is precise for the valuation of vanilla options. We generalize the affine decomposition to other non-affine stochastic volatility models with polynomial drift and volatility functions, and with jumps in the volatility process.

Keywords: Log-normal stochastic volatility, Jumps in price and volatility, Model calibration, Closed-form solution, Option pricing, Quadratic variance, Econometric Estimation

JEL Classification: G13, C63

Suggested Citation

Sepp, Artur, Log-Normal Stochastic Volatility Model: Affine Decomposition of Moment Generating Function and Pricing of Vanilla Options (March 7, 2016). Available at SSRN: https://ssrn.com/abstract=2522425 or http://dx.doi.org/10.2139/ssrn.2522425

Artur Sepp (Contact Author)

Sygnum Bank's Asset Management ( email )

Uetlibergstrasse 134a
Zurich, 8045
Switzerland

HOME PAGE: http://artursepp.com

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