Herding and Power Laws in Financial Markets

Abstract

This study provides an explanation of the emergence of power laws in trading volume and asset returns. In the model, traders infer other traders’ private signals regarding the value of an asset from their actions and adjust their own behavior accordingly. When the number of traders is large and the signals for asset value are noisy, this leads to power laws for equilibrium volume and returns.
We also provide numerical results showing that the model reproduces observed distributions of daily stock volume and returns.