We give a stochastic microscopic modelling of stock markets driven by
continuous double auction. If we take into account the mimetic behavior of
traders, when they place limit order, our virtual markets shows the power-law
tail of the distribution of returns with the exponent outside the Levy stable
region, the short memory of returns and the long memory of volatilities. The
Hurst exponent of our model is asymptotically 1/2. An explanation is also given
for the profile of the autocorrelation function, which is responsible for the
value of the Hurst exponent.Comment: 7 pages, 8 figure