Rationalizing Trading Frequency and Returns: Maybe Trading is Good for You

Yosef Bonaparte, Russell Cooper, Mengli Sha
National Bureau of Economic Research,Issue w25838,
Barber and Odean study the relationship between trading activity and returns. They find that households who trade more have a lower net return than other households. They argue that these results cannot emerge from a model with rational traders and instead attribute these findings to overconfidence. In contrast, we find that household financial choices generated from a dynamic optimization problem with rational agents and portfolio adjustment costs can produce trading and return patterns that closely mimic these facts. Adding various forms of irrationality, modelled as beliefs about income and return processes that are not data based, do not improve the ability of the model to explain the patterns of turnover and net returns. Irrationality can improve the ability of the model to match a larger set of moments, including these turnover and net return moments coupled with those that capture the wealth to income ratio and portfolio composition.