On December 16, 2011, at 11:09:51.500 and again at 11:33:46.190, quotes from ISE flooded OPRA for approximately 50 to 100ms. During these events, there were no quotes from any of the other 9 reporting exchanges.
We'd also like to point out an anomaly in quote rates from the ISE exchange that appears whenever the total OPRA quote rate exceedes about 3 million quotes/sec. When OPRA quotes surge to a peak, the quote rate from ISE will suddenly back off and stay low until the total quote rate declines, where upon it will suddenly surge, often sending total OPRA traffic to new highs.
The second ISE flood event at 11:33:46.190.
The 48 OPRA Lines during the first ISE flood event.
Zooming and showing the 48 OPRA Lines during the first ISE flood event.
The 7 charts below show the ISE quote surge anomaly.
Note the consistent pattern in the red line. This anomaly occurs often: whenever the total OPRA quote nears it's capacity limitation. (C2, BATS, and BOX exchange not show to reduce clutter).