Critical Ising Model and Financial Market

Takeshi Inagaki

Published 2004-02-20, updated 2004-02-22Version 2

We investigate Ising model description of dynamics of stock price. The model is defined in near 2 dimensions, one dimension is time and another represents ensemble of stocks, and strength of response of investors to price change corresponds to inverse temperature of the system. At critical temperature, infinitely long correlation among number of trades along time is observed and power-law tail in distribution of price fluctuation appears.