Robust pricing and hedging under trading restrictions and the emergence of local martingale models

We pursue the robust approach to pricing and hedging in which no probability measure is fixed, but call or put options with different maturities and strikes can be traded initially at their market prices. We allow the inclusion of robust modelling assumptions by specifying a set of feasible paths on...

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Main Authors: Cox, A, Hou, Z, Obloj, J
Format: Journal article
Published: Springer Berlin Heidelberg 2016
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author Cox, A
Hou, Z
Obloj, J
author_facet Cox, A
Hou, Z
Obloj, J
author_sort Cox, A
collection OXFORD
description We pursue the robust approach to pricing and hedging in which no probability measure is fixed, but call or put options with different maturities and strikes can be traded initially at their market prices. We allow the inclusion of robust modelling assumptions by specifying a set of feasible paths on which (super)hedging arguments are required to work. In a discrete-time setup with no short selling, we characterise absence of arbitrage and show that if call options are traded, then the usual pricing–hedging duality is preserved. In contrast, if only put options are traded, a duality gap may appear. Embedding the results into a continuous-time framework, we show that the duality gap may be interpreted as a financial bubble and link it to strict local martingales. This provides an intrinsic justification of strict local martingales as models for financial bubbles arising from a combination of trading restrictions and current market prices.
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spelling oxford-uuid:c1f0a802-7f71-4734-a9c9-325d8dc9b3b02022-03-27T06:05:17ZRobust pricing and hedging under trading restrictions and the emergence of local martingale modelsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:c1f0a802-7f71-4734-a9c9-325d8dc9b3b0Symplectic Elements at OxfordSpringer Berlin Heidelberg2016Cox, AHou, ZObloj, JWe pursue the robust approach to pricing and hedging in which no probability measure is fixed, but call or put options with different maturities and strikes can be traded initially at their market prices. We allow the inclusion of robust modelling assumptions by specifying a set of feasible paths on which (super)hedging arguments are required to work. In a discrete-time setup with no short selling, we characterise absence of arbitrage and show that if call options are traded, then the usual pricing–hedging duality is preserved. In contrast, if only put options are traded, a duality gap may appear. Embedding the results into a continuous-time framework, we show that the duality gap may be interpreted as a financial bubble and link it to strict local martingales. This provides an intrinsic justification of strict local martingales as models for financial bubbles arising from a combination of trading restrictions and current market prices.
spellingShingle Cox, A
Hou, Z
Obloj, J
Robust pricing and hedging under trading restrictions and the emergence of local martingale models
title Robust pricing and hedging under trading restrictions and the emergence of local martingale models
title_full Robust pricing and hedging under trading restrictions and the emergence of local martingale models
title_fullStr Robust pricing and hedging under trading restrictions and the emergence of local martingale models
title_full_unstemmed Robust pricing and hedging under trading restrictions and the emergence of local martingale models
title_short Robust pricing and hedging under trading restrictions and the emergence of local martingale models
title_sort robust pricing and hedging under trading restrictions and the emergence of local martingale models
work_keys_str_mv AT coxa robustpricingandhedgingundertradingrestrictionsandtheemergenceoflocalmartingalemodels
AT houz robustpricingandhedgingundertradingrestrictionsandtheemergenceoflocalmartingalemodels
AT oblojj robustpricingandhedgingundertradingrestrictionsandtheemergenceoflocalmartingalemodels