An Eigenfunction Approach for Volatility Modeling

Nour Meddahi

Cahiers de recherche from Universite de Montreal, Departement de sciences economiques

Abstract: In this paper, we introduce a new approach for volatility modeling in discrete and continuous time. We follow the stochastic volatility literature by assuming that the variance is a function of a state variable. However, instead of assuming that the loading function is ad hoc (e.g., exponential or affine), we assume that it is a linear combination of the eigenfunctions of the conditional expectation (resp. infinitesimal generator) operator associated to the state variable in discrete (resp. continuous) time. Special examples are the popular log-normal and square-root models where the eigenfunctions are the Hermite and Laguerre polynomials respectively. The eigenfunction approach has at least six advantages: i) it is general since any square integrable function may be written as a linear combination of the eigenfunctions; ii) the orthogonality of the eigenfunctions leads to the traditional interpretations of the linear principal components analysis; iii) the implied dynamics of the variance and squared return processes are ARMA and, hence, simple for forecasting and inference purposes; (iv) more importantly, this generates fat tails for the variance and returns processes; v) in contrast to popular models, the variance of the variance is a flexible function of the variance; vi) these models are closed under temporal aggregation.

Keywords: volatility; stochastic volatility; infinitesimal generator; conditional exctation; eigenfunctions; ARMA; fat tails; GMM (search for similar items in EconPapers)
JEL-codes: C50 C51 C52 (search for similar items in EconPapers)
Pages: 44 pages
Date: 2001
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (76)

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http://hdl.handle.net/1866/368 (application/pdf)

Related works:
Working Paper: An Eigenfunction Approach for Volatility Modeling (2001)
Working Paper: An Eigenfunction Approach for Volatility Modeling (2001)
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Persistent link: https://EconPapers.repec.org/RePEc:mtl:montde:2001-29

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