Whereas historical stock/future ticks represent a time, price and volume at which a trade was transacted, I understand FX ticks are different; they represent a time, and two quotes, the best bid and best ask across some sample of quotes at a time immediately after one or other of the two quotes changes. Soâ¦ ticks (and bars) for stocks and futures are based on actual trades; but ticks (and bars) for FX are based only on âbestâ quotes. Is this correct? And for those ETers that test systematic FX strategies, does the above difference also imply there should be differences too between the methodology of using historical data to test and evaluate a FX strategy, and that used for a stock/futures strategy? Or is it irrelevant?