If one were to measure the Bid/Ask changes (not quote updates, but an actual shift in price of the Bid/Ask to the next level (either up or down)) per minute on stocks/futures/whatever. What would have the highest number? I would like to exclude anything that doesn't consistently maintain a tight spread. My guess is that CL would have the highest number of those that I've come across. Are there any others that you can think of? While I haven't written any sort of tool to measure this. It is only based on observation. Has anyone seen any actual studies for this sort of thing? Thanks!