From the CME website:
|Image from ZeroHedge|
And here is the FedEx attack:
FEDex Tick chart. Notice the the run up in price between 9:36 and 9:37
Nasdaq Trading Through NYSE Example
According to a system status message on February 13th 2012:
NASDAQ, NASDAQ BX, and NASDAQ PSX would like to advise their customers of an issue that took place earlier today. Because of an internal issue, all three markets would not have protected the New York Stock Exchange (N) quote from 09:30:00 ET until the issue was resolved at 09:40 ET. As a result, it is possible that some orders could have traded through, or not have been routed to, the NYSE quote when it was at the inside.Here is an example.
10 millisecond chart of Fedex (FDX) showing Nasdaq quotes (black shading), Nasdaq trades (black circles), NYSE quotes (blue shading) and NYSE trades (blue circles).
And for those who missed the HFT Party headline, enjoy this tune.