A behavioural finance perspective on trade imbalanceand stock prices

Abstract

In this thesis I examine, within a behavioural finance framework, the impact on stock prices of order and trade imbalance in three separate but related studies. The first study, chapter two, begins with a question that plagues behavioural finance theories do the investors most likely to be influenced by the behavioural biases described in the literature, i.e., individual investors, affect stock prices? My data enable me to consider the impact of net individual investor trading for the entire market over several years. I find that net individual investor purchasing Granger causes stock price changes. The correlation is negative, however, contradicting common sense by demonstrating that individuals investor buying pressure makes prices go down and selling pressure forces them up. More investigation is required. Chapter three references order imbalance results from experimental finance. I use field data to test a robust laboratory model and my modified versions. My findings suggest that, with appropriate modifications, laboratory results can be applied to real financial markets. Chapter four combines the data from the chapters two and three to revisit the question of individual investor impact on stock prices. Other studies have argued that individual investor influence is strongest in smaller capitalization stocks. Moreover, various theories propose that individual investors are the driving force behind the irrational stock prices of a bubble. I focus on the stocks from chapter three, bubble stocks, and ask whether, in the context of the trading of the entire market, individual investor trades are influential. Once again I find Granger causality, but in the wrong direction. Moreover, the activity and volume of the individual investor category of the holdings data is completely overshadowed by that of the two large investor categories, domestic and foreign institutions. I conclude that individual investor trades are not influential in determining stock prices. This conclusion has important implications for some behavioural finance models of asset pricing. I suggest that emphasis might be better placed on educating individual investors about the errors to which they are prone, rather than on trying to explain market anomalies with those errors.