Statistical physics of induced correlation in a simple market

A simple model for the collective behaviour of diverse speculative agents in a competitive market is considered from the point of view of statistical physics. The only information about other agents available to any one is the total trade effected at each time-step. Evidence is presented for correlated adaptation, phase transitions, scaling, regimes of non-equilibration and equilibration, and relevant stochasticity. An intermediate-level quasi-continuous micro-dynamics is derived and shown to have a novel character.