Price Drops, Fluctuations, and Correlation in a Multi-Agent Model of   Stock Markets
  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. 
A.G. Zawadowski, R. Karadi, J. Kertesz