  We show power-scaling behaviors for fluctuations in share volume, which no
other studies have so far done. After analyzing a database of the daily
transactions for all securities listed on the Tokyo Stock Exchange, we selected
1050 large companies that each had an unbroken series of daily trading activity
from January 1975 to January 2002. We found that the cumulative distributions
of daily fluctuations in share volumes can be well described by a power-law
decay, and that the cumulative distributions for almost all of the companies
can be characterized by an exponent within the stable Levy domain. Furthermore,
more than 35 percent of the cumulative distributions can be well approximated
by Zipf's law, that is, the cumulative distributions have an exponent close to
unity.
