SEC Follow Up Exhibits Part C SEC_OEA_FCIC_001760-2501

Reg SHO Pilot Report 2/12/2007
Table 3: Changes in Short Selling Activity
This table summarizes how short selling changes when the tick and bid tests are removed. The four months prior to
the Pilot start date (May 2, 2005) are called the “Pre-Pilot” and the six months following the start date are called the
“Pilot”. The table shows the average change in short selling for Pilot and Control stocks and estimates whether the
Pilot stocks changed more than the Control stocks. Short Volume is the number of shares in short sale transactions
divided by total share volume. Short Trades is the number of short sale transactions divided by total transactions.
Short Interest is the monthly short interest times 100 divided by the shares outstanding. Days to Cover is the
monthly short interest divided by the average daily share volume during the corresponding month. Nasdaq market
share is Nasdaq’s share of the volume of short selling. Paired t-tests determine whether the changes are significant.
Tests of the difference between the changes are two-sample t-tests. **, * indicates statistical significance at the 1
and 5% level in a two-tailed test. We test whether the Difference in the Change for Listed Stocks is statistically
different from that of Nasdaq NM Stocks using a regression framework. During the Pilot Period, we run daily crosssectional
regressions of each variable on an indicator for Pilot Securities and the variable’s pre-Pilot level (equation
1). We run the regression separately for Listed and Nasdaq NM Stocks and test whether the coefficients on the Pilot
indicator are similar. a, b indicates that the average coefficient for Nasdaq NM Stocks is statistically different from
the average coefficient for Listed Stocks at the 1% and 5% level in a two-tailed test.
Panel A: Univariate Changes
Pilot Sample Control Sample Pilot Δ minus
Variable Market Pre-Pilot Pilot Δ Pre-PIlot Pilot Δ Control Δ
Short Volume Listed 24.41 26.32 1.91** 24.27 24.16 -0.11 2.02**
Short Volume Nasdaq 36.08 37.76 1.68** 35.55 35.75 0.20 1.48**
Short Trades Listed 27.37 33.67 6.30** 27.15 26.79 -0.36* 6.66**
Short Trades Nasdaq 37.74 39.98 2.24** 37.20 37.57 0.37* 1.87**
Short Interest Listed 3.62 4.01 0.39** 3.75 4.25 0.49** -0.10
Short Interest Nasdaq 5.23 5.94 0.71** 5.00 5.60 0.60** 0.11
Days to Cover Listed 6.14 6.87 0.73** 6.28 7.03 0.75** -0.02
Days to Cover Nasdaq 6.64 7.91 1.27** 6.49 8.07 1.58** -0.31
Nasdaq Market Share Listed 10.74 10.28 -0.46* 10.42 11.17 0.75** -1.21**
Nasdaq Market Share Nasdaq 47.45 51.34 3.88** 47.86 49.20 1.34** 2.55**
Panel B: Average Regression Coefficients
Market Quality i = α + β Pilot 1 i + β Pre Pilot Market Quality
2
i
Variable Market Pilot PrePilotControl R-squared
Short Volume
Short Volume
Listed
Nasdaq
2.05**
1.67**
0.61** 0.09
a
0.67** 0.08
Short Trades
Short Trades
Listed
Nasdaq
6.75**
2.08**
0.63** 0.16
a
0.67** 0.10
Short Interest
Short Interest
Listed
Nasdaq
-0.11
0.14
0.89** 0.83
a
0.91** 0.79
Days to Cover
Days to Cover
Listed
Nasdaq
-0.05
-0.31
0.74** 0.49
b
0.97** 0.62
Nasdaq Market Share
Nasdaq Market Share
Listed
Nasdaq
-1.18**
2.34**
0.77** 0.15
a
0.69** 0.11
Prepared by the Office of Economic Analysis 62