  In this paper we compare market price fluctuations with the response to
fundamental price drops within the Lux-Marchesi model which is able to
reproduce the most important stylized facts of real market data. Major
differences can be observed between the decay of spontaneous fluctuations and
of changes due to external perturbations reflecting the absence of detailed
balance, i.e., of the validity of the fluctuation-dissipation theorem. We found
that fundamental price drops are followed by an overshoot with a rather robust
characteristic time.
