  In this paper we quantitatively investigate the statistical properties of an
ensemble of {\it 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 < \alpha < 2.2 $.
