Diversity and relative arbitrage in equity markets

Robert Fernholz (), Ioannis Karatzas () and Constantinos Kardaras ()

Finance and Stochastics, 2005, vol. 9, issue 1, 27 pages

Abstract: An equity market is called “diverse” if no single stock is ever allowed to dominate the entire market in terms of relative capitalization. In the context of the standard Itô-process model initiated by Samuelson (1965) we formulate this property (and the allied, successively weaker notions of “weak diversity” and “asymptotic weak diversity”) in precise terms. We show that diversity is possible to achieve, but delicate. Several examples are provided which illustrate these notions and show that weakly-diverse markets contain relative arbitrage opportunities: it is possible to outperform or underperform such markets over any given time-horizon. The existence of this type of relative arbitrage does not interfere with the development of contingent claim valuation, and has consequences for the pricing of long-term warrants and for put-call parity. Several open questions are suggested for further study. Copyright Springer-Verlag Berlin/Heidelberg 2005

Keywords: Financial markets; portfolios; diversity; relative arbitrage; order statistics; local times; stochastic differential equations; strict local martingales (search for similar items in EconPapers)
Date: 2005
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Citations: View citations in EconPapers (61)

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DOI: 10.1007/s00780-004-0129-4

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