Do some future brokers take the other side of a market execution for a poor fill? Example, lets say I place a market order to buy NQ, and I get filled at 18000.25? But the ask has been at 18000 even and never has moved off of that. Essentially they are taking a quarter for themselves. (I know for limits, the order resides at the CME and out of the broker's hand in that situation)
My quick response is no. All CME retail orders today trade on the CME through Globex. There are no Futures Dark pools. That said, the CME does have their CME ClearPort for institutional orders. On that system, it is possible for the broker or FCM if they have a trade desk to provide liquidity. https://www.cmegroup.com/clearport.html
NQ tick size is less than a nanometer! You can't see it unless you use a powerful scanning electron microscope. Next point to consider : How fast/clean is the data feed going to your platform? If you trade the regulated exchange, there is less thing to worry about.
No one like to pay market data and transaction fees. I'm impressed with what the CME offers. A large number of symbols, supported by a stable structure with GREAT customer support. In addition, they are you counter party after settlement. They offer a vast number of free services on their website to promote education on Futures and Options on futures. And, if you want to lower your transaction fees, you can buy or lease a membership. Hard to do all that in a for profit company and do it for less.
I'm all for paying market data and transaction fees but I'm against one company controlling almost all US futures. Competition often serves as a driving force for innovation.
Or some researchers from the brokers told clients to buy while the big money (like those investment banks) took the other side