May 6'th 2010 Flash Crash Analysis
Continuing Developments
SEC Report Response
An inspection of several key items included or omitted from the SEC's
Final Flash Crash Report.
Publication Date: 10/13/2010
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Table Of Contents
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I. Waddell & Reed Sell Algorithm
The SEC report identified a Sell Algorithm selling 75,000 contracts as the
primary cause of the flash crash. If the "Sell Algorithm" in the SEC
report refers to the Waddell & Reed trades, then there is a problem.
Sell
Algo Trades - Analysis of the Waddell & Reed (W&R) May 6, 2010 trade
executions.
II. NYSE Delays
Page 76 of the SEC's Final Flash Crash Report states:
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- Between 2:44:45 p.m. and 2:46:29 p.m. on May 6, NYSE quotes in the 1665
Symbols had average delays to the CQS of over 10 seconds. Between 2:45 p.m. and
2:50 p.m., over 40 of the 1665 Symbols had an average delay to CQS of more than
20 seconds, and the average delay for all of the 1665 Symbols was just over 5
seconds.
- NYSE also experienced delays disseminating transaction information to
the consolidated feed and through at least one of its proprietary data feeds.
Between 2:45 p.m. and 2:50 p.m.
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As reported in our
Initial
Flash Crash Report and
Flash
Crash Summary Report, the delays in NYSE stocks began at 14:42:45. We
are not sure why the report mentions the first delay time 2 minutes later, when
delays already exceeded 10 seconds. The delays started 2 minutes earlier and
gradually built up to 10+ seconds in about 1/2 of the symbols.
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As shown above, the final plunge of the day corresponds precisely to when
the NYSE began to delay quotes. This fact was omitted from the report.
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III. The NBBO
As we have reported, as the NYSE quotes that were lagging were time stamped as
current, CQS
(responsible for determining the NBBO) would designate NYSE quotes as the
NBBO even though the quotes were stale and crossed with other
markets.
On 05/06/2010 there were approx 3,300 stock listed on the NYSE exchange. As
1665 stock were determined to have delays and were incorrectly designated as
the NBBO, approx. 50% off all stocks listed on the NYSE had incorrect NBBO
pricing. Therefore any analysis using the NBBO for these stocks after 14:42:45
would be invalid.
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From Page 80:
In this report we have extended our analyses to include the full order books
of many thousands of securities and ETFs. To do so we obtained NYSE OpenBook
Ultra and NYSE ArcaBook data, Nasdaq ModelView and similar data from BATS.
These sources provided minute-by-minute snapshots of the order
book, for all listed securities.71 These data allowed us to calculate the
number of shares represented by buy and sell limit orders on these exchanges at
a wide range of price points. We measured the price points in terms of the
relative distance from the midpoint of the NBBO. These data provide a detailed
picture of the available liquidity for each security, throughout the day.
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From Page 83:
ORDER DEPTH. The blue bars show the market depth for resting buy-side
orders, and the green bars show the depth for resting sell-side orders. There
is a separate bar for each minute during trading hours, and the height of the
bars in the lightest shades show the number of shares available for
purchase/sale within 10 basis points of the midpoint of the NBBO.
...For each security there are two sets of charts: the first presents
liquidity limited to within 500 bp of the NBBO midpoint, and the second
presents all available liquidity. |
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From Page 84:
From 2:43 p.m. through 2:44 p.m., selling liquidity fell sharply, perhaps as
orders were executed, and buying liquidity declined less, so that at 2:44 p.m.,
there were approximately 33,000 shares with orders to purchase within 500 bp of
the NBBO midpoint, but only approximately 22,000 shares with orders to sell
within 500 bp. |
IV. Importance of CQS/CTS
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From Page 38:
Most of the firms we interviewed that are concerned with data latency in the
milliseconds (such as market makers, internalizers, and HFTs) subscribe
directly to the proprietary feeds offered by the exchanges. These firms do not
generally rely on the consolidated market data to make trading decisions and
thus their trading decisions would not have been directly affected by the delay
in data in this feed. However, some of these firms do use the consolidated
market data feeds for data-integrity checks, and delay-induced data
discrepancies certainly contributed to the general sense of unease experienced
that day.
Other firms that are not concerned with data latency in the milliseconds (such
as many asset managers and other lower-frequency traders) tend to rely on the
consolidated market data feeds for trading decisions. A number of those
interviewed reported pulling back from the market as general volatility
increased, and those seeing delays and price-discrepancies on the consolidated
market data feeds did report that was a contributing factor in their decision
to curtail or halt further trading. The source and potential implications of
data delays in the consolidated market data feeds will be explored further in
Section 3.
From Page 76:
The CTS and CQS systems represent a consolidated view of trading and
top-of-book quoting across all national exchanges and ECNs, and trading at
internalizers and dark pools. As such, the relative timing of trades and quotes
within these systems are subject to some aggregation delays, which generally
are less than 10 milliseconds. As discussed in Section 2, many large market
participants route orders directly to exchanges and subscribe to the
proprietary feeds from each exchange in order to minimize aggregation delays
and receive depth-of-book quotes. Accordingly, automated systems making trading
decisions based on these feeds should not have been directly affected by delays
in the CTS and CQS system. It is important to note that retail order flow is
generally handled by internalizers who are also among those participants that
use proprietary exchange feeds to make trading and routing decisions.
However, firms that use proprietary feeds to make trading decisions may still
have been impacted by delays on the CTS and CQS feeds. As discussed, concerns
about data integrity contributed to pauses or halts in many automated trading
systems, which in turn led to a reduction in general market liquidity. Most
firms reported to us that the primary drivers of their integrity-based halts
were observed, rapid changes in the E-Mini and observed, rapid changes in
individual securities.But data-integrity checks based on the CTS and CQS feeds
would have been directly affected by delays in the consolidated market data,
and firms using those integrity-checks reported that this influenced, and to
some extent supported, their decisions to pause or halt trading.
For firms employing trading strategies that are less time-sensitive, and whose
automated systems rely solely on data from the CQS and CTS, data delays on
these feeds could have directly triggered integrity-pauses. Some such firms
reported that delays on the CQS and CTS were a more significant part, though
not the sole reason, for their decision to curtail or halt trading on the
afternoon of May 6. We note, however, that while these types of firms are not
generally market makers or liquidity providers, they can be significant
fundamental buyers and sellers. |
Shown above are four paragraphs (from two separate pages) regarding how many
firms were effected by CQS/CTS and in fact influenced by CQS/CTS in trade
decisions, regardless of receiving premium feeds, CQS/CTS or both.
Again from page 78:
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Our investigation to date reveals that the largest and most erratic
price moves observed on May 6 were caused by withdrawals of liquidity and the
subsequent execution of trades at stub quotes. ...However, the evidence does
not support the hypothesis that delays in the CTS and CQS feeds triggered or
otherwise caused the extreme volatility in security prices observed that day.
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Loss of liquidity really means buyers pulled out -- few buyers means lower
prices. The reason the buyers pulled out? As evident by the SEC's statements
above, one of the primary reasons was lack of confidence in data integrity and
much of that was due to delays experienced on the NYSE.
In regards to volatility levels when trades began to hit stub quotes, actual
execution of trades at stub quotes did not begin to occur until the market had
bottomed and played no role in the actual crash itself.
Furthermore, from Page 76:
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Rule 603(b) of Regulation NMS requires equity exchanges and FINRA to act
jointly to disseminate consolidated information, including an NBBO, on
quotations for and transactions in NMS stocks. The consolidated information is
disseminated through securities information processors that collect, process,
and prepare for publication such information including the price, size, and
symbol of quotations and executions. |
As stated in Item II of this report, approx. 50% of all NYSE stocks had
incorrect NBBO values after 2:42:45. A simple search for "NBBO" in
the report is all that is needed to determine how much of the analysis relies
on the NBBO (and NBBO mid-point). Given this, 50% of the analysis in the report
which uses the NBBO for NYSE listed stocks after 14:42:45 must be considered
void, as the NBBO was incorrect. This should underscore the importance of
CQS/CTS.
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V. Time Stamping of Quote Data
As we reported in both our
Initial
Flash Crash Report and
Flash
Crash Summary Report, when quotes from the NYSE were lagging the
market, they were time stamped when disseminated from CQS and not when the
orders were placed. Therefore the orders appeared to be current (which led to
the NYSE
bids being designated as the NBBO even though they were severely
crossed with other markets). This was a key issue -- the lag in NYSE quotes was
not detected and sell order flow routed to the NYSE.
Proper time stamping of quotes should be the cornerstone of market structure
and should apply equally to both proprietary exchange feeds and CQS/CTS. When
quotes that are 20 seconds (or more) behind the real market and time stamped as
current, the ability to detect latency in that feed is diminished
significantly. This is most likely the reason no one knew the NYSE feed was
delayed (including the NYSE).
Changing the current procedure to time stamp at the time a quote or trade is
generated is a near trivial exercise. It probably comes as a surprise to many
that time stamping isn't done this way now. In both our
initial
and summary
reports we make this recommendation.
Despite the ramifications of incorrect time stamping, the issue is not
addressed in the report.
VI. Data Used
There are currently 11 reporting exchanges for US securities (NYSE, Nasdaq,
ISE, BATS, Boston, Cincinnati (National Stock Exchange), CBOE, ARCA, Chicago,
EDGX and EDGA). The SEC report analyzed data from 5 exchanges which represented
90% of trade executions on 05/06/2010.
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Page 80:
In this report we have extended our analyses to include the full order books
of many thousands of securities and ETFs. To do so we obtained NYSE OpenBook
Ultra and NYSE ArcaBook data, Nasdaq ModelView and similar data from BATS.
These sources provided minute-by-minute snapshots of the order
book, for all listed securities. These data allowed us to calculate the number
of shares represented by buy and sell limit orders on these exchanges at a wide
range of price points. We measured the price points in terms of the relative
distance from the midpoint of the NBBO. These data provide a detailed picture
of the available liquidity for each security, throughout the day.
In addition, we obtained order audit trail files from several sources,
including NYSE, NYSE Amex, NYSE Arca, Nasdaq and BATS, each containing detailed
data on orders received, modified, canceled, and executed. In total, this data
contained 5.3 billion records.
These exchanges, combined, reflect approximately 90% of the executions on
exchanges on May 6.
Page 47-48:
To assess HFT trading during the market decline in a more comprehensive
fashion, we also examined a data set obtained from the largest public quoting
markets on May 6 each of the equities exchanges and Direct Edge (EDGA
and EDGX). This data included total dollar volume on those markets across all
securities by 15-minute increments, and was further categorized according to
liquidity-taking and liquidity-providing buys and sells. Specific participant
data was also provided for each executing broker-dealer that was among the top
20 48 May 6, 2010 Market Event Findings aggressive sellers on each market
during the rapid price decline on May 6. From this list of aggressive sellers,
we aggregated data for 17 executing broker-dealers that appear to be primarily
associated with HFT firms in order to compare trading patterns of these firms
with the rest of the market. The group should not be used to extrapolate the
overall percentage of trading volume of HFTs because it does not include, for
example, the proprietary trading desks of multi-service broker-dealers that may
engage in HFT strategies. Moreover, this data set does not include trading in
the OTC market (except for Direct Edge). |
The majority of the analysis appears to have been conducted with 1 minute
shapshot data or 15 minute interval data. At best, one minute snap-shot data
shows what the data looked like at the end of (or start of -- the report does
not specify) each minute. 5,000 stocks using one-minute snap-shot data would
represent 5,000 data points. However, actual exchange data would represent 12
million data points. So essentially, 1/2400 of the data available was examined.
In regards to the analysis of HFT trading using 15 minute data increments, many
HFT algorithms quote at rates exceeding 5,000 orders per second.
VII. Other Omissions
- Quote Saturation
The
quote
saturation event that triggered delays in the NYSE and CQS/CTS are
absent from the report. From our Flash Crash Summary Report:
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It appears that the event that sparked the rapid sell off at 14:42:44:075
was an immediate sale of approximately $125 million worth of June 2010 CME
eMini futures contracts (not originating from Waddell & Reed) followed 25ms
later by the immediate sale of over $100 million worth of the top ETF's such as
SPY, DIA, QQQQ, IVV, IWM, SDS, XLE, and EEM. Both the eMini and ETF sales were
sudden and executed at prevailing bid prices. The orders appeared to hit the
bids. The volume in these sales are not considered to be extreme.
However, approximately 400ms before the eMini sale, the quote traffic rate for
all NYSE, NYSE Arca, and Nasdaq stocks surged to saturation levels within 75ms.
This is a new and surprising discovery. Previously, when we looked at time
frames below 1 second, we thought the increase in quote traffic coincided with
the heavy sales, but we now know that the surge in quotes preceded the trades
by about 400ms. The discovery is surprising, because nearly all the trades in
the eMini and ETFs occurred at prevailing bid prices (a liquidity removing
event).
The quote traffic surged again during the ETF sell event and remained at
saturation levels for nearly 500ms. Additional selling waves began seconds
later sending quote traffic rates back to saturation levels. This tidal wave of
data caused delays in many feed processing systems and networks. We discovered
two notable delays: the NYSE network that feeds into CQS (the "NYSE-CQS
Delay"), and the calculation and dissemination of the Dow Jones Indexes
(DOW Delay).
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- As we also show in our Flash Crash Summary report, the
DJI
(Dow Jones Industrial Average) also became significantly delayed for 2
reasons:
- Delay in the input data (NYSE-CQS delay) and the methodology used in
computing the DJI - they only use prices of trades from the NYSE for NYSE
component stocks.
- A second and larger delay appears to originate within the feed processors
that compute the index values. To find the second delay, we calculated DJI
using the same methodology as Dow Jones and compared the result to the value
disseminated in the feed. Our prices during the periods prior to and shortly
after the crash matched the prices disseminated by Dow Jones; however, during
the crash, we noticed significant delays. We confirmed the prices of DJI in the
feed matched or were ahead of other sources.
No mention is made of the DJI delay in the report.
- A near identical occurrence of the Flash Crash one week prior to
05/06/2010.
As we reported, on
04/28/2010
the market experienced a "Mini Flash Crash" with near
identical circumstances as 05/06/2010.
Analysis of 04/28/2010 and any correlation it might have to the events of
05/06/2010 are absent from the report.
- We note there was no mention of
Options
in the report, .
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Publication Date: 10/13/2010
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