  It is suggested to consider long term trends of financial markets as a growth
phenomenon. The question that is asked is what conditions are needed for a long
term sustainable growth or contraction in a financial market? The paper discuss
the role of traditional market players of long only mutual funds versus hedge
funds which take both short and long positions. It will be argued that
financial markets since their very origin and only till very recently, have
been in a state of ``broken symmetry'' which favored long term growth instead
of contraction. The reason for this ``broken symmetry'' into a long term ``bull
phase'' is the historical almost complete dominance by long only players in
financial markets. Dangers connected to short trading are illustrated by the
appearence of long term bearish trends seen in analytical results and by
simulation results of an agent based market model. Recent short trade data of
the Nasdaq Composite index show an increase in the short activity prior to or
at the same time as dips in the market, and reveal an steadily increase in the
short trading activity, reaching levels never seen before.

Statistical Mechanics;Trading and Market Microstructure