On Geometrically Convex Risk Measures

Fuente: arXiv
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Autores principales: Aygün, Mücahit, Bellini, Fabio, Laeven, Roger J. A.
Formato: Preprint
Publicado: 2024
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author Aygün, Mücahit
Bellini, Fabio
Laeven, Roger J. A.
author_facet Aygün, Mücahit
Bellini, Fabio
Laeven, Roger J. A.
contents Geometrically convex functions constitute an interesting class of functions obtained by replacing the arithmetic mean with the geometric mean in the definition of convexity. As recently suggested, geometric convexity may be a sensible property for financial risk measures ([7,13,4]). We introduce a notion of GG-convex conjugate, parallel to the classical notion of convex conjugate introduced by Fenchel, and we discuss its properties. We show how GG-convex conjugation can be axiomatized in the spirit of the notion of general duality transforms introduced in [2,3]. We then move to the study of GG-convex risk measures, which are defined as GG-convex functionals defined on suitable spaces of random variables. We derive a general dual representation that extends analogous expressions presented in [4] under the additional assumptions of monotonicity and positive homogeneity. As a prominent example, we study the family of Orlicz risk measures. Finally, we introduce multiplicative versions of the convex and of the increasing convex order and discuss related consistency properties of law-invariant GG-convex risk measures.
format Preprint
id arxiv_https___arxiv_org_abs_2403_06188
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On Geometrically Convex Risk Measures
Aygün, Mücahit
Bellini, Fabio
Laeven, Roger J. A.
Risk Management
Probability
91B06, 26A51, 52A41
Geometrically convex functions constitute an interesting class of functions obtained by replacing the arithmetic mean with the geometric mean in the definition of convexity. As recently suggested, geometric convexity may be a sensible property for financial risk measures ([7,13,4]). We introduce a notion of GG-convex conjugate, parallel to the classical notion of convex conjugate introduced by Fenchel, and we discuss its properties. We show how GG-convex conjugation can be axiomatized in the spirit of the notion of general duality transforms introduced in [2,3]. We then move to the study of GG-convex risk measures, which are defined as GG-convex functionals defined on suitable spaces of random variables. We derive a general dual representation that extends analogous expressions presented in [4] under the additional assumptions of monotonicity and positive homogeneity. As a prominent example, we study the family of Orlicz risk measures. Finally, we introduce multiplicative versions of the convex and of the increasing convex order and discuss related consistency properties of law-invariant GG-convex risk measures.
title On Geometrically Convex Risk Measures
topic Risk Management
Probability
91B06, 26A51, 52A41
url https://arxiv.org/abs/2403.06188