An Intuitive Introduction to Fractional and Rough Volatilities

Elisa Alòs and Jorge A. León
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Elisa Alòs: Department d’Economia i Empresa, Universitat Pompeu Fabra, and Barcelona GSE c/Ramon Trias Fargas, 25-27, 08005 Barcelona, Spain
Jorge A. León: Departamento de Control Automático, CINVESTAV-IPN, Apartado Postal 14-740, 07000 México City, Mexico

Mathematics, 2021, vol. 9, issue 9, 1-22

Abstract: Here, we review some results of fractional volatility models, where the volatility is driven by fractional Brownian motion (fBm). In these models, the future average volatility is not a process adapted to the underlying filtration, and fBm is not a semimartingale in general. So, we cannot use the classical Itô’s calculus to explain how the memory properties of fBm allow us to describe some empirical findings of the implied volatility surface through Hull and White type formulas. Thus, Malliavin calculus provides a natural approach to deal with the implied volatility without assuming any particular structure of the volatility. The aim of this paper is to provides the basic tools of Malliavin calculus for the study of fractional volatility models. That is, we explain how the long and short memory of fBm improves the description of the implied volatility. In particular, we consider in detail a model that combines the long and short memory properties of fBm as an example of the approach introduced in this paper. The theoretical results are tested with numerical experiments.

Keywords: derivative operator in the Malliavin calculus sense; fractional Brownian motion; future average volatility; Hull and White formula; Itô’s formula; Skorohod integral; stochastic volatility models; implied volatility; skews and smiles; rough volatility (search for similar items in EconPapers)
JEL-codes: C (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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