Fair points re: the SIP. However, that submission is the benchmark for fairness is unfortunate. There is no reason it needs to be that way, and fixing it and di

Fair points re: the SIP. However, that submission is the benchmark for fairness is unfortunate. There is no reason it needs to be that way, and fixing it and distributing the SIP (i.e., removing the centralized processor) has numerous advantages that put to rest the latency, fairness and SPOF issue. In that regime, measuring "same" becomes simple. Measure at the source the venue specific SIP feed (which contains the venue's view of NBBO) and the depth of book feed delta. Over the course of a day, that delta should effectively be 0. You're absolutely right about the SEC website issue. It's silly to get upset about this since the "web" aspect of the distribution has so many layers.