hi Dave,
we use every exchange out there plus bank feeds. but these things happen across
banks and exchanges, especially the banks. You would not believe the quality of bank data feeds. Their answer is just to widen the spreads if there is large volatility. I think that is because they have lots of computerised trading system logged onto their platforms to try and hit them if there is a price disparity. we do not we only accept retail flows so we can sanity check the process a lot easier. also we need to maintain a high level of service to our clients. I can tell you on forex for example that during a volatile period for the most part we offer better quotes than we receive from the banks. A classic example was when the Swiss National Bank put a floor on euro/chf of 1.20. the bank feeds went crazy (so did ours) but for the most part we offered our clients a better spread than we were receiving.
tks pc