There has been intensive research on the impact and e¤ects of the SEC regulation
reform on trading structure. Barclay et al [4] have examined the impact
and e¤ects of market reform on the trading costs and depths on Nasdaq stocks.
Their major result was that the restructuring of Nasdaq market have produced
a more competitive and e¢cient trading system on Nasdaq. The authors quanti…
ed the impact of these new rules on various performance and e¢ciency indicators
such as trading costs and liquidity. They found that quoted and e¤ective
spreads fell dramatically without a¤ecting the market e¢ciency.
The target of theses reforms was to o¤er to investors more competitive
quotes through the mandatory display of customer limit orders and the dissemination
of superior prices placed in ECN. Although this new reform was
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general, it has been targeting towards Nasdaq. In general, quoted and e¤ective
spreads, trading volume, quoted depth and other measures of liquidity indicate
that e¢ciency has substantially been improved.
Quoted and e¤ective spreads have narrowed by approximately 30 percent,
with the largest bene…t to stocks with wide spread prior to the SEC’s 1997
impositions. Overall trading costs have declined by sixty percent in the period
from January 1994 to February 1997.
However, this reduction seems to have appeared before the introduction of
the new rules and is largely attributed to the various government investigations
and negative publicity directed at Nasdaq. The similarity in trading cost reductions
for the stocks phased in on January 20 and February 10 implies that
the savings stem from the display of limit orders and quotes from proprietary
trading systems rather than from the decline in minimum quote sizes.
The reduction in the minimum quote size has had important e¤ects on measure
of depth. The average trade size decline for stocks with a minimum quote
size of 100 shares. The frequency of 1,000 shares trades is dramatically lower,
o¤set by proportionally larger frequencies of smaller trade sizes, particularly
100 shares trades. Thus, as dealers post smaller quote sizes as principals or
smaller sized limit orders as agents, average trade sizes decline, particularly
among trades executed through the Small Order Execution System (SOES).
Interestingly, general market depth has been adversely a¤ected. Barclay et al
[4] estimated a ”quote” book using the posted depths and bid-ask quotes from
individual dealers and ECN to compute execution costs assuming that trades
are executed against the posted depths. They found the average round-trip
costs declined by almost 30 percent, with large reduction across all trade-size
categories. Their interesting result is that although trade-sizes at the narrower
spreads decline, the total quoted size in close proximity to the bid-ask midpoint
increases.
Finally, the Excess Spread Rule (ESR) change a¤orded dealers greater ‡exibility
in determining the width of their individual spreads by having to conform
to monthly rather than continuous requirements. Modifying this rule had no
material e¤ect on quoted or e¤ective inside spreads. However, there has been
an increasing number of quote revisions, along with an increase in both the
average dealer spread and the variability of spread across dealers.