Are behavioral biases stable across markets and prevalent across individuals? : evidence from individual betting choices

We use novel data on individual activity in a sports betting market to study the effect of past performance sequences on individual behavior in a real market. The revelation of fundamental values in this market enables us to disentangle whether behavior is caused by sentiment or by superior information about market mispricings, hence to cleanly test in a real setting two sentiment-based theories of momentum and reversals — the regime-shifting model of Barberis, Shleifer, and Vishny (1998) and the gambler's/hot-hand fallacy model of Rabin (2002). Furthermore, our long panel allows us to calculate the proportions of individuals who exhibit each type of behavior. We find that i) three quarters of individuals exhibit trend-chasing behavior; ii) seven times as many individuals exhibit behavior consistent with Barberis, Shleifer, and Vishny (1998) as exhibit behavior consistent with Rabin (2002); and iii) no individuals earn superior returns from momentum trading