Overreaction, Momentum, Liquidity, and Price Bubbles in Laboratory and Field Asset Markets

Abstract

Laboratory asset markets provide an experimental setting in which to observe investor behavior. Over more than a decade, numerous studies have found that participants in laboratory experiments frequently drive asset prices far above fundamental value, after which the prices crash. This bubble-and-crash behavior is robust to variations in a number of variables, including liquidity (the amount of cash available relative to the value of the assets being traded), short-selling, certainty or uncertainty of dividendpayments, brokerage fees, capital gains taxes, buying on margin, and others.

This paper attempts to model the behavior of asset prices in experimental settings by proposing a "momentum model" of asset price changes. The model assumes that investors follow a combination of two factors when setting prices: fundamental value, and the recent price trend. The predictions of the model, while still far from perfect, are superior to those of a rational expectations model, in which traders consider only fundamental value. In particular, the momentum model predicts that higher levels of liquidity lead to larger price bubbles, a result that is confirmed in the experiments. The similarity between laboratory results and data from field (real-world) markets suggests that the momentum model may be applicable there as well.