Presentation Transcript

1. Arturo Bris “Short Selling Activity in Financial Stocks and the SEC July 15th Emergency Order”

   Discussion by Ian Marsh, Cass Business School
2. Short Sales For once academics largely agree on a topic Short sales are a good thing since in theory they improve market efficiency, are integral to key asset pricing models, prevent bubbles and may even prevent crashes Empirical evidence is also largely supportive of this view But most of this literature is based on financial markets in normal times
3. Short Sales Restrictions Recent regulatory moves on short selling have been made in distinctly non-normal times Arturo’s paper focuses on the SEC Emergency Order brought in July 15th, effective July 21-August 15th, 2008 Norman Niemer and I wrote a paper in November 2008 looking at the effects of the global tightening of short sales constraints mid-September 2008
4. Compare and Contrast Bris, Goetzmann and Zhu (JFin, 2007) X-sectional and time series evidence from 46 countries 1990-2001 Bris (2008) G19 through time and against control groups of US FIs and non-US FIs Marsh and Niemer (2008) 17 countries, varying levels of SS restrictions, before and after restrictions, restricted and unrestricted firms
5. Marsh and Niemer Counterfactuals Compare returns distributions of (financial) firms subject to SS restrictions to returns of Those same firms before the restrictions (so differing by time period analysed) Firms not subject to the restrictions (so differing by type of firm but same time period) Financial (and NF) firms in different jurisdictions (so differing by nationality but same type of firm, same period) None of these are ideal
6. Dimensions Average returns and volatilites Arguably the reason why regulators intervened Not obvious that SS restrictions have much impact Skewness and kurtosis of returns Crash risk measures Probable that SS restrictions might be detected here Market efficiency Expected cost of SS restriction is reduction in market quality
7. Average returns and short selling Arturo finds that an increase in short interest reduces returns Relatively poor performance of G19 stocks is not due to short selling, but rather dismal operating performance Norman and I find that: Returns on portfolio of US financial stocks significantly worse after ban on SS Poor but not abnormal (compared to rest of 2008) for UK financials
8. Volatility and short selling Arturo finds: Volatility increases 150% after EO We find: UK and US financials subject to SS ban saw huge increases in volatility Non-financials also saw significant increases from a lower starting level to a lower ending level Return and volatility patterns are repeated globally, including France and Germany where restrictions were less binding, and Japan and Sweden where restrictions were unchanged
9. Volatility (StdDev portfolio returns)
10. Conclusions #1 While vols and returns change around the EO and the September ban it is hard to link these to short selling activities or regulatory changes Bad news is (eventually) priced by the equity markets There was a lot of bad news about for markets to price during 2008
11. Crash risk and short selling BGZ: Skewness is positive and larger in the presence of SS restrictions Large negative returns are no more frequent if SS allowed Shorting associated with extreme returns that become more negative not more frequent negative returns Marsh-Niemer: Changes in skew not systematic Skew is not at all unusual post ban Kurtosis is generally lower post ban (not UK financials) but this is true for all companies and irrespective of nature of the restrictions
12. Skewness
13. Kurtosis
14. Market efficiency and short selling BGZ: R2 and cross-autocorrelation results suggest SS allow faster impounding of bad news into prices Arturo: Quoted spreads increased for G19 stocks after EO much more than for unaffected stocks BGZ-style indicators indicate decline in efficiency after EO, very slightly more so for G19 Marsh-Niemer: No impact of SS ban on autocorrelations
15. Conclusions #2 BGZ suggest some support for regulator view that SS restrictions reduce negative skewness of returns but this comes at the cost of lower market quality Bris and Marsh-Niemer find that while market quality has declined across regulatory changes it doesn’t appear to be caused by the changes And the changes didn’t seem to alter returns distributions
16. Conjectures To me, the surprise is that SS restrictions had such little effect on market quality Reasons: Small samples Effect of restrictions swamped by event effects Other ways of taking short bets on stocks had emerged (eg CDS)
17. Looking forward Arturo Looking at stock lending activities globally Interesting preliminary results suggesting strategic stock lending Me Looking at liquidity provision at microstructure level By far the strongest result I saw relating to Sept08 was the decimation of trading volume after the ban