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No Arbitrage Criteria for Exponential L évy Models. A.V. Selivanov Moscow State University. Financial Mathematics. 3 ”columns” (Z. Bodie, R.C. Merton ”Finance”) :. air. Mathematical : A – set of incomes. No Free Lunch (NFL) (J.M. Harrison, D.M. Kreps 1979). Concept of No Arbitrage.
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No Arbitrage Criteriafor Exponential Lévy Models A.V. SelivanovMoscow State University
Financial Mathematics 3 ”columns” (Z. Bodie, R.C. Merton ”Finance”):
air • Mathematical:A – set of incomes No Free Lunch (NFL) (J.M. Harrison, D.M. Kreps 1979) Concept of No Arbitrage • Practical:
– any sequence, NFL No Arbitrage condition in discrete time Fundamental Theorem of Asset Pricing: • J.M. Harrison, S.R. Pliska 1981 – finite W • R.C. Dalang, A. Morton, W. Willinger 1990 – general case
No Arbitrage conditions in continuous time • No Free Lunch with Vanishing Risk (NFLVR)F. Delbaen, W. Schachermayer 1994 • No Generalized Arbitrage (NGA)A.S. Cherny 2004
Definition of sigma-martingales The definition is given by T. Goll and J. Kallsen • A semimartingale M is a sigma-martingale if there exist predictable sets such that • or • is a uniformly integrable martingale for any n
Sigma-martingales and local martingales sigma-martingales local martingales positive sigma-martingales
S– any process, integrable martingale} Classes of Martingale Measures
existence of certainmartingale measure absence of arbitrage completeness of the model uniqueness of the measure
Models under consideration • exponential Lévy model: • time-changed exponential Lévy model: L – nonzero Lévy process – independent increasing non-constant process
Black-Scholes and Merton models • Black-Scholes modelB– Brownian motion, • Merton model – Poisson process,
Theorem for model (1) with infinite time horizon NFLVR always GA
Theorem for model (2) with infinite time horizon Suppose that P-a.s. Then always GA.
An example: NFLVR and GA NFLVR is satisfied;NGA is not satisfied Strategy:
Conclusions We have obtained: • the criteria for the NFLVR and the NGA conditions for models with finite time horizon;for these models • the criteria for the NFLVR and the NGA conditions for models without time change and with infinite time horizon; for these models the NGA is never satisfied, while the NFLVR is satisfied in certain cases