The Cost of Overconfidence in Public Information

We investigate the effects of investor overconfidence in public information on cross-sectional asset returns. The results show that investors in the US equity market are overconfident about public signals for mature firms that are relatively easy to price—old, large, and dividend-paying firms, value firms, and firms with a higher proportion of tangible assets, little external financing, and low sales growth. However, the effects of the overconfidence on cross-sectional stock returns are reversed quickly and comprise more than half of the short-term return reversals. The risk-adjusted cost of being overconfident about the noisy public signals, measured by return reversals of hedge portfolios formed on unexpected responses, is over 1.1% per month in the first month after portfolio formation, and is still significant despite the active arbitrage trading in the 2000s.