On Azéma-Yor processes, their optimal properties and the Bachelier-drawdown equation

We study the class of Az\'ema-Yor processes defined from a general semimartingale with a continuous running maximum process. We show that they arise as unique strong solutions of the Bachelier stochastic differential equation which we prove is equivalent to the drawdown equation. Solutions of t...

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Main Authors: Carraro, L, Karoui, N, Obloj, J
Format: Journal article
Published: 2009
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author Carraro, L
Karoui, N
Obloj, J
author_facet Carraro, L
Karoui, N
Obloj, J
author_sort Carraro, L
collection OXFORD
description We study the class of Az\'ema-Yor processes defined from a general semimartingale with a continuous running maximum process. We show that they arise as unique strong solutions of the Bachelier stochastic differential equation which we prove is equivalent to the drawdown equation. Solutions of the latter have the drawdown property: they always stay above a given function of their past maximum. We then show that any process which satisfies the drawdown property is in fact an Az\'ema-Yor process. The proofs exploit group structure of the set of Az\'ema-Yor processes, indexed by functions, which we introduce. We investigate in detail Az\'ema-Yor martingales defined from a nonnegative local martingale converging to zero at infinity. We establish relations between average value at risk, drawdown function, Hardy-Littlewood transform and its inverse. In particular, we construct Az\'ema-Yor martingales with a given terminal law and this allows us to rediscover the Az\'ema-Yor solution to the Skorokhod embedding problem. Finally, we characterize Az\'ema-Yor martingales showing they are optimal relative to the concave ordering of terminal variables among martingales whose maximum dominates stochastically a given benchmark.
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spelling oxford-uuid:fcaabcab-e63e-4c39-85b1-05025669086b2022-03-27T13:22:38ZOn Azéma-Yor processes, their optimal properties and the Bachelier-drawdown equationJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:fcaabcab-e63e-4c39-85b1-05025669086bSymplectic Elements at Oxford2009Carraro, LKaroui, NObloj, JWe study the class of Az\'ema-Yor processes defined from a general semimartingale with a continuous running maximum process. We show that they arise as unique strong solutions of the Bachelier stochastic differential equation which we prove is equivalent to the drawdown equation. Solutions of the latter have the drawdown property: they always stay above a given function of their past maximum. We then show that any process which satisfies the drawdown property is in fact an Az\'ema-Yor process. The proofs exploit group structure of the set of Az\'ema-Yor processes, indexed by functions, which we introduce. We investigate in detail Az\'ema-Yor martingales defined from a nonnegative local martingale converging to zero at infinity. We establish relations between average value at risk, drawdown function, Hardy-Littlewood transform and its inverse. In particular, we construct Az\'ema-Yor martingales with a given terminal law and this allows us to rediscover the Az\'ema-Yor solution to the Skorokhod embedding problem. Finally, we characterize Az\'ema-Yor martingales showing they are optimal relative to the concave ordering of terminal variables among martingales whose maximum dominates stochastically a given benchmark.
spellingShingle Carraro, L
Karoui, N
Obloj, J
On Azéma-Yor processes, their optimal properties and the Bachelier-drawdown equation
title On Azéma-Yor processes, their optimal properties and the Bachelier-drawdown equation
title_full On Azéma-Yor processes, their optimal properties and the Bachelier-drawdown equation
title_fullStr On Azéma-Yor processes, their optimal properties and the Bachelier-drawdown equation
title_full_unstemmed On Azéma-Yor processes, their optimal properties and the Bachelier-drawdown equation
title_short On Azéma-Yor processes, their optimal properties and the Bachelier-drawdown equation
title_sort on azema yor processes their optimal properties and the bachelier drawdown equation
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