Investor overconfidence, characterized by an excessive belief in the ability to generate superior portfolio returns, is a widely studied behavioral bias. This paper investigates the mechanisms underlying overconfidence using a Bayesian model that incorporates two features: biased prior beliefs, which imply overconfidence even before investors engage in the stock market, and biased learning, where investors overemphasize instances of outperforming the market. Empirical analysis supports the hypothesis that biased learning contributes to overconfidence, but only in the early years of investor tenure. Although overconfidence decreases with investment experience, we find that it is a widespread and persistent behavioral trait.

We study the financial behavior of minorities over 2007-09. We find that after 2008 and compared to White Americans, African Americans and Hispanics have a higher propensity to increase risk tolerance, optimism, and allocations to risky assets and lower probability of exiting the stock market. These findings cannot be explained by changes in wealth or income, and we speculate that they may be due to the positive effects of the election of President Obama. Specifically, we find that the change in behavior by minorities from 2007 to 2009 is consistent with minorities updating their beliefs about future economic outcomes.