  The collective phenomena of a liquid market is characterized in terms of a
particle system scenario. This physical analogy enables us to disentangle
intrinsic features from purely stochastic ones. The latter are the result of
environmental changes due to a `heat bath' acting on the many-asset system,
quantitatively described in terms of a time dependent effective temperature.
The remaining intrinsic properties can be widely investigated by applying
standard methods of classical many body systems. As an example, we consider a
large set of stocks traded at the NYSE and determine the corresponding
asset--asset `interaction' potential. In order to investigate in more detail
the cluster structure suggested by the short distance behavior of the
interaction potential, we perform a connectivity analysis of the spatial
distribution of the particle system. In this way, we are able to draw
conclusions on the intrinsic cluster persistency independently of the specific
market conditions.
