Power law for ensembles of stock prices

In this paper, we quantitatively investigate the statistical properties of an ensemble of stock prices. We selected 1200 stocks traded in the Tokyo Stock Exchange and formed a statistical ensemble of daily stock prices for each trading day in the 5 year period from January 4, 1988 to December 30, 1992. We found that the tail of the complementary cumulative distribution function of the ensembles is accurately described by a power-law distribution with an exponent that moves in the range of 1.7<α<2.2.