Swedroe: Short-Sellers Have Key Market Role

Swedroe: Short-Sellers Have Key Market Role

Short-sellers help improve market efficiency and provide useful data.

Reviewed by: Larry Swedroe
Edited by: Larry Swedroe

The academic literature demonstrates that short-sellers, while often demonized, play an important role in the capital markets. For example, short-sale constraints prevent pessimistic opinions from being fully reflected in stock prices, thereby allowing optimistic investors to drive prices above intrinsic value.

In fact, research has found that short-sellers are able to anticipate the public revelation that a company has misstated its financial statements and can predict negative earnings surprises, analyst downgrades and other negative company news. Additionally, researchers have found that expensive-to-short stocks (where borrowing fees are high) have low subsequent returns.

Findings such as these have led some “passive” money management firms (such as AQR, Bridgeway, and Dimensional Fund Advisors in its long-only funds) to suspend purchases of stocks that are “on special” (that is, where securities lending fees are very high).

Short Selling And Bonds
Stephen Christophe, Michael Ferri, Jim Hsieh and Tao-Hsien Dolly King, authors of the April 2015 paper “Short Selling and Cross-Section of Corporate Bond Returns,” contribute to the literature on short-selling by examining the impact of the short-selling of a company’s stock on that firm’s bonds.

They matched short-selling data with 156 individual bond issues available during their sample period, which ran from September 13, 2000 to July 10, 2001. The authors acknowledge the limitation that, “due to the propriety nature of the data,” their “sample period is relatively short.”

Their paper begins by noting:

  • Most corporate bonds are held by institutional investors and money managers, whereas stockholders are a more diverse group.
  • While the equity market is followed closely by financial analysts and the popular press, the corporate bond market is followed by a smaller number of sell-side bond analysts, and thus receives less coverage.
  • Although a bond’s creditworthiness is assessed by bond rating agencies, it is often observed that ratings significantly lag firm performance.

The authors then hypothesize that “the greater liquidity of the equity market and the stronger presence of unsophisticated retail investors could induce informed traders to use equity short selling as the primary tool for profiting from negative information about the overall firm because the market’s characteristics allow them to more easily disguise their trades. Moreover, if a negative information shock affects a firm’s fundamentals, which in turn changes its expected cash flows and/or risk, both stock and bond prices should decline. This anticipated reaction is quite intuitive, since both stocks and bonds represent claims on a company’s future cash flows.”


Following is a summary of their findings:

  • Both shorting activity and the size of short trades are inversely correlated with contemporaneous bond returns.
  • Firms with heavily shorted shares or large short trade size experience significantly negative bond returns in the future. A 1 percentage point increase in shorting activity results in a 0.60% decline in bond returns in the subsequent month. The authors write: “The results are statistically significant, and their economic magnitudes are quite large.”
  • The negative future valuation effect associated with heavy shorting is even more pronounced for high-yield bonds, which, on average, experience a 1.34% price decline. When short trades are large, high-yield bonds experience returns 1.69% lower than the returns for investment-grade bonds. And after partitioning the high-yield bonds into quartiles based on the average size of the firm’s short trades, contemporaneous bond returns for the largest quartile are, on average, 1.66% lower than those for the smallest quartile.
  • The relationship between short trade size and subsequent bond returns is consistent with the stealth trading of short-sellers.
  • The impact of both shorting activity and short trade size on bond returns is robust to various controls for risk, liquidity and other pricing factors.
  • Firms associated with heavy short selling or large short trade size are likely to subsequently experience negative earnings surprises, higher credit risk and reduced dividends.

The authors noted that their results were consistent with prior studies finding that short interest increases in the month preceding a bond rating downgrade. They concluded that “the overall results support the proposition that short trades in the equity market exert important valuation consequences in the corporate bond market.”


The bottom line is that short-sellers play a valuable role in keeping market prices efficient. And market efficiency is important because an efficient market allocates capital efficiently. If short sellers were inhibited from expressing their views on valuations, securities prices could become overvalued and excess capital would then be allocated to those firms. The evidence presented in this paper also demonstrates the strong link between the equity risk associated with a firm’s stock and the credit risk associated with the same company’s bonds.

Larry Swedroe is the director of research for The BAM Alliance, a community of more than 140 independent registered investment advisors throughout the country.


Larry Swedroe is a principal and the director of research for Buckingham Strategic Wealth, an independent member of the BAM Alliance. Previously, he was vice chairman of Prudential Home Mortgage.