> However even fixed-delays [1] can still create uncertainty about what price your order may actually execute at when it hits the server, which is something HFT

> However even fixed-delays [1] can still create uncertainty about what price your order may actually execute at when it hits the server, which is something HFTs rely on more heavily than other traders, since their strategy depends on high-certainty that they will have a small positive margin on every trade This is also true on every single other exchange, albeit to a smaller degree. You have a larger queue of possible things that may have happened, but this issue exists everywhere. No exchange has instant entry. On a very short timescale things are very jumpy - nothing happens for a while, and then everything happens all at once. The queuing problem tends to be more of “did another hft beat me to the same event”, not general random other events, so queues like IEXs tend to be emptyish anyways.