Nanex did some digging into market data before the Nasdaq blackout at 12:20 EDT on August 22, 2013. They discovered several significant periods of extremely high quote volume. By plotting the number of messages for each of the 6 multicast lines used by the Tape C SIP (Securities Information Processor), we discovered the quote blasts map directly to individual multicast lines.
Note that this is the data feed that Nasdaq claimed as the source of he bad data.
“The first chart above plots the number of messages for each multicast line between 10:50 and 12:10 EDT. Note there are several message surges: each of which is confined to an individual multicast lines (single color). The surge on line #6 at 10:55 (red line) is from zeroed bids and asks from ARCA (this is detailed in another chart below). The 3 surges at 11:48 (blue), 11:50 (red) and 11:54 (green) are actually from a resending of the previous 50 minutes worth of quotes as if they were new quotes. Each quote had a new timestamp and marked as if it were real-time – which caused these quotes to update the NBBO! We detail this in the stock ORLY in 2 below.”
We are slowly destroying the core structure of our capital markets.