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

These rumors do not circulate in all directions, but essentially from the top to the bottom of society. The rather sophisticated presentations, the apparently serious references that seem to justify their origins, and their distinguished proponents provide food for amplifications serving diverse interests and psychological biases in all layers of society.

The old Wall Street saying " buy on rumors, sell on the news," is alive and well, as can be seen from numerous sources in the media and the Internet. Rumors can drive herding behavior strongly.

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.