The Effect of Short Sale Ban on the Relation between Disagreement and Stock Returns

This paper investigates the effect of the short sale ban by the Korean government on the relationship between the disagreement among investors and the future stock returns. Short selling in Korean stock market was banned twice in 2008 and 2011. The short sale ban provides a natural experiment environment to study the effect of the short sale constraints on the relationship between the disagreement among investors and the future stock returns. Furthermore, it is an exogenous shock in the point of individual stocks. Thus, this paper focus on short sale ban periods to analyzes the stock return predictability of the disagreement among investors’ opinions about analysts’ earnings forecasts. Main results of this paper are as follows: First, the portfolio within the top 30% of the disagreement among investors experiences the significantly higher returns than that within the bottom 30% of the disagreement only during short sale ban periods. However, the two portfolio returns are not significantly different during the other periods excluding the short sale ban periods. These results are robust even after controlling for firm sizes, boot to market ratios, and the momentum effects. Second, a portfolio with higher the disagreement among investors presents significantly positive abnormal returns estimated by Fama-French’s three factor model during short sale ban periods. On the other hand, the abnormal returns of the portfolio with lower the disagreement among investors are not significantly different from zero. Furthermore, those returns of the portfolio with lower disagreement are not affected by the short sale ban. Finally, our findings show that individual stock returns are positively related to disagreement after controlling for the characteristics of individual stocks. Consequentially, the stocks with higher disagreement are overvalued during the short sale ban periods according to our robust empirical analyses with various control variables. According to our findings, we conclude that the short sale constraints are important factors to determine the predictability of disagreement on future stock returns. These are consistent with the results of short sale ban on the U.S. stock market from Autore, Billingsley, and Kovacs (2011).