An Intuitive Introduction to Fractional and Rough Volatilities

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 cl...

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Main Authors: Elisa Alòs, Jorge A. León
Format: Article
Language:English
Published: MDPI AG 2021-04-01
Series:Mathematics
Subjects:
Online Access:https://www.mdpi.com/2227-7390/9/9/994
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author Elisa Alòs
Jorge A. León
author_facet Elisa Alòs
Jorge A. León
author_sort Elisa Alòs
collection DOAJ
description 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.
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spelling doaj.art-79d2c21f75eb4f64b2d9de545a13e4022023-11-21T17:31:34ZengMDPI AGMathematics2227-73902021-04-019999410.3390/math9090994An Intuitive Introduction to Fractional and Rough VolatilitiesElisa Alòs0Jorge A. León1Department d’Economia i Empresa, Universitat Pompeu Fabra, and Barcelona GSE c/Ramon Trias Fargas, 25-27, 08005 Barcelona, SpainDepartamento de Control Automático, CINVESTAV-IPN, Apartado Postal 14-740, 07000 México City, MexicoHere, 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.https://www.mdpi.com/2227-7390/9/9/994derivative operator in the Malliavin calculus sensefractional Brownian motionfuture average volatilityHull and White formulaItô’s formulaSkorohod integral
spellingShingle Elisa Alòs
Jorge A. León
An Intuitive Introduction to Fractional and Rough Volatilities
Mathematics
derivative operator in the Malliavin calculus sense
fractional Brownian motion
future average volatility
Hull and White formula
Itô’s formula
Skorohod integral
title An Intuitive Introduction to Fractional and Rough Volatilities
title_full An Intuitive Introduction to Fractional and Rough Volatilities
title_fullStr An Intuitive Introduction to Fractional and Rough Volatilities
title_full_unstemmed An Intuitive Introduction to Fractional and Rough Volatilities
title_short An Intuitive Introduction to Fractional and Rough Volatilities
title_sort intuitive introduction to fractional and rough volatilities
topic derivative operator in the Malliavin calculus sense
fractional Brownian motion
future average volatility
Hull and White formula
Itô’s formula
Skorohod integral
url https://www.mdpi.com/2227-7390/9/9/994
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