Perhaps the most profound synthesis of physical sciences came from the realization that everything could be understood from "conservation laws" and s… - Didier Sornette

The same basic ingredients are found repeatably: fueled by initially well founded economic fundamentals, investors develop a self-fulfilling enthusiasm by an imitative process or crowd behavior that leads to an unsustainable accelerating overvaluation.

Since it is the actions of investors whose buy and sell decisions move prices up and down, any deviation from a random walk has ultimately to be traced back to the behavior of investors.

One trader's move in the market can be interpreted by another trader as relevant additional information due to the uncertainty he faces.