A generalized spin model of financial markets |
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Authors: | D Chowdhury D Stauffer |
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Institution: | Institute for Theoretical Physics, University of Cologne, 50923 K?ln, Germany, DE
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Abstract: | We reformulate the Cont-Bouchaud model of financial markets in terms of classical “super-spins” where the spin value is a
measure of the number of individual traders represented by a portfolio manager of an investment agency. We then extend this
simplified model by switching on interactions among the super-spins to model the tendency of agencies getting influenced by the opinion of other managers. We also introduce
a fictitious temperature (to model other random influences), and time-dependent local fields to model a slowly changing optimistic
or pessimistic bias of traders. We point out close similarities between the price variations in our model with N super-spins and total displacements in an N-step Levy flight. We demonstrate the phenomena of natural and artificially created bubbles and subsequent crashes as well
as the occurrence of “fat tails” in the distributions of stock price variations.
Received 13 October 1998 |
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Keywords: | PACS 05 50 +q Lattice theory and statistics Ising problems - 89 90 +n Other areas of general interest to physicists |
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