Short Sale Constraints, Dispersion of Opinion, and Market Quality: Evidence from the Short Sale Ban on U.S. Financial Stocks

Abstract

The three-week ban on short selling during 2008 for nearly 800 U.S. financial stocks provides an opportunity to directly test how binding short sale constraints affect stock valuation. We focus on the relative valuation effects of the ban on stocks with higher vs. lower dispersion of investor opinion and stocks that experience greater vs. smaller deterioration in market quality. First, we find that the initiation of the ban is associated with abnormal price increases that continue even after the ban. Second, valuation increases are significantly more pronounced for stocks associated with greater dispersion of opinion. However, after the ban is removed, this dispersion effect disappears. Third, the ban is associated with large increases in relative quoted spreads and decreases in the average number of trades per day, consistent with a reduction in market quality. Finally, the banned stocks that face the greatest widening in their spread experience weaker abnormal stock performance during and after the ban. In summary, the dispersion-related findings support Miller’s (1977) argument that high dispersion stocks become overvalued under binding short sale constraints. The spread-related findings suggest that short sellers are viewed as informed investors. In the absence of short sellers, investors demand higher risk premiums to reflect the increased uncertainty about the stock’s value. From a policy standpoint, the actions of the Securities and Exchange Commission might have curbed excessive price declines for troubled firms without lasting differential valuation consequences for higher vs. lower dispersion stocks. However, these policy actions had severe market quality consequences. (JEL G12, G14, G18, G28) Short Sale Constraints, Dispersion of Opinion, and Market Quality