Avery, Christopher N., Judith A. Chevalier, and Richard J. Zeckhauser. "The “CAPS” Prediction System and Stock Market Returns." Review of Finance (September 2015): 1-19.
We study approximately 5.0 million stock picks submitted by individual users to the “CAPS” website run by the Motley Fool company (www.caps.fool.com). These picks prove to be surprisingly informative about future stock prices. Shorting stocks with a disproportionate number of negative picks and buying stocks with a disproportionate number of positive picks yields a return of over 12% per annum over the sample period. Negative picks mostly drive these results; they strongly predict future stock price declines. Returns to positive picks are statistically indistinguishable from the market. A Fama–French decomposition suggests that stock-picking rather than style factors largely produced these results.