maybe the knee jerk reaction on HN is to think 'HFT' but this really isn't. although i have to say 400ms to place an order, cancel it, and place a new order in

maybe the knee jerk reaction on HN is to think 'HFT' but this really isn't. although i have to say 400ms to place an order, cancel it, and place a new order in the opposite direction (or 2 actions using the cancel-if-cross - all manually as it appears - is pretty fast. high frequency finger clicking, maybe, but definitely not high frequency. the cftc is going after this guy for the behaviour that resulted from the avoid-orders-that-cross feature that was available on that guy's commercial trading platform (the application is TT and it's used everywhere), and in the sarao case they went after his cancel-if-close behaviour too (that too is sort-of available direct from some exchanges - pegged order). i hope they know that the industry has plenty of available tools to help the average joe do things like these because they have their own meaningful (but specific) purpose in day to day trading. in this particular case- cme and a lot of other exchanges really really don't like it if you cross your own orders. it reeks of wash trading. this is just a tool to make it really simple, because sometimes a firm has multiple traders that have different trades they want to put on and you can't always be sure they won't cross each other. sometimes i wonder if the tools proliferate these malicious behaviour or if the malicious behaviour proliferate these tools. i suspect a lot of market participants are engaging in very "aggressively defensive" behaviour to counter things like these. in any case the microstructure has changed quite a bit in as quickly as the last 10 months and it looks like that is going to be the new normal rate of change.