Quote from Pekelo:
Again, I am not saying those are not market orders. I am saying one can not tell...
Also why wouldn't they use limit orders, when they can be sure it gets filled immediatelly, if aimed at the Ask. But it is insurance against a bad fill 2-3 ticks away.
When ES is moving on extreme up and down spike you can miss the chance of getting a good fill if a program goes off right before or when when you drill the bid or ask with a limit. Not usually a problem for a small retail trader.
