Herd Behavior in a Laboratory Financial Market

We study herd behavior in a laboratory Þnancial market where a sequence of subjects trades an asset whose value is unknown. In two treatments the price is updated according to a deterministic rule based on the order ßow, and in another it is updated by experimental participants. Theory predicts that agents should never herd. Our experimental results are in line with this prediction. Nevertheless, we observe a phenomenon that cannot be accounted for by the theory. In some cases, subjects decide not to use their private information and choose not to trade. In other cases, they ignore their private information to trade against the market (contrarian behavior). (JEL