  We discuss recent work in the study of a simple model for the collective
behaviour of diverse speculative agents in an idealized stockmarket, considered
from the perspective of the statistical physics of many-body systems. The only
information about other agents available to any one is the total trade at time
steps. Evidence is presented for correlated adaptation and phase
transitions/crossovers in the global volatility of the system as a function of
appropriate information scaling dimension. Stochastically controlled
irrationally of individual agents is shown to be globally advantageous. We
describe the derivation of the underlying effective stochastic differential
equations which govern the dynamics, and make an interpretation of the results
from the point of view of the statistical physics of disordered systems.
