Learning Fast or Slow?

Rational models claim “trading to learn” explains widespread excessive speculative trading and challenge behavioral explanations of excessive trading. We argue rational learning models do not explain speculative trading by studying day traders in Taiwan. Consistent with previous studies of learning, unprofitable day traders are more likely to quit than profitable traders. Consistent with models of overconfidence and biased learning (but not with rational learning), the aggregate performance of day traders is negative, 74% of day trading volume is generated by traders with a history of losses, and 97% of day traders are likely to lose money in future day trading