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07/27/2011 - Direct Feed Slowdown (Latency) on Demand

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We have analyzed book level data, a direct feed from a prominent exchange, for May 6, 2010. The same data the SEC used for the October 2010 report on the flash crash. It took about 3 hours for us to discover what the SEC either missed or chose to omit:  this direct feed experienced significant delays and showed all the signs of being overloaded. There is a very clear relationship between message traffic and the extent and duration of the delay. Anyone who has worked with market data would have easily discovered this revelation within a day or two. The SEC report even mentions an average delay for this direct feed which makes the omission even more troubling.

This discovery is important because it illustrates how someone could cause latency in a direct exchange feed whenever they wanted: simply send and cancel orders at a high enough rate. A rate that turns out to be, not very high. Last year we published a report about a similar mechanism we discovered on an inbound line into CQS. We now believe other direct feeds also exhibit delays when message rates exceed a threshold. It would seem to us, that having detailed information on the relationship between message rate and delay would be vital for HFT firms to compete.

Someone could slow down a direct exchange feed whenever they want, by simply sending and canceling orders at a high enough rate.

We also found that activity increases to a maximum, and then falls off significantly beginning at 14:42:44; this is extraordinary given that the market was about to drop 600 points in one of the most violent sell-offs ever recorded. This also just happens to be the exact point in time where an aggressive algorithm started and without regard to the precarious state of the market, violently sold a few thousand S&P 500 futures contracts and simultaneously, sold a few hundred million dollars worth of ETFs, such as SPY, IWM, QQQ, and DIA. This is long before any stub quotes or liquidity replenishment points or the infamous hot-potato game began.

We think it is time for a Senator or Representative to call for an investigation on how such obvious and key pieces of evidence could have been omitted from the findings. Findings that are now driving new regulations. Is it wise to base regulations on a faulty understanding of what you are trying to regulate?

The first set of charts illustrate the relationship between quote message traffic and delay in a direct exchange feed on May 6, 2010. We count the number of new and canceled orders for each 20ms period and plot this as a blue line, scaled in messages/second (msg/s). We also take an average of the difference between the Source and Send time fields, and plot this as a red line scaled in microseconds: a value of 25,000 means the average delay was 25,000 microseconds or 25 milliseconds during the interval.

Note the strong correlation between message rate and delay: whenever traffic exceeds approximately 100,000 msg/s (indicated by the horizontal red line), a delay appears. The extent and duration of the delay is proportional to the extent and duration that traffic exceeds this threshold. We discovered this within 3 hours of receiving the data; it was trivial to find. 

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The next chart shows peak message rate and delay in the direct feed from 14:00 to 15:00 on May 6th, 2010. Note how often the delay (red line) peaks right at 200,000 microseconds: this is very suspicious and merits additional investigation. Many delays also appear near 35,000 microseconds. Finally, note how often the peaks in message rate are at the same level: this is a common phenomenon on saturated networks.

3 Second Peak Message Rate and Delay

The next chart shows the collapse of activity begin at 14:42:44. This is a plot of order messages (quotes) and order executions (trades) averaged over 1 second intervals.

1 Second Average Quote and Trade Rates on Direct Exchange Feed


1 Second Average Quote and Trade Rates on Direct Exchange Feed (zoomed in)

For reference, the next chart shows prices for SPY, an ETF representing stocks in the S&P 500. Circled is is the trigger point at 14:42:44.

Chart of SPY


Publication Date: 07/27/2011

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