Quote from robbie25:
No. They have nothing to do with the MM. The only way fees become an issue is if you are directly accesing the exchanges themselves. If you ARE doing that, then you are not necessairily trading with the MM's (although you may be). In fact, in some ways, you are now competing WITH the MM's.
As for the fees themselves, each ECN has a fee schedule that it either charges (or pays) you for volume. Generally, the ECN's will pay you if you ADD liquidity (for example, place a bid at or below the highest bid....if you then get filled, you have added liq.) and charge you if you Rremove it (for example, if you cross the spread and buy at the asking price)
Each ECN (there are lots) has different fees, and you need to choose your gateway based on what you plan on doing.
Important to note, remembr I said that 'generally' ECN's pay you to add liq. and charge to remove. That is not always the case though. The Boston Exchange (BOSX on L2) actually does the opposite, that is, they pay you to remove liquidity, and charge you to add. I believe the current fees are chargin 0.0002 to AL but rebating 0.0001 RL
In comparison, the ARCA gateway charges 0.0023 to RL but rebates 0.002 to AL.
You can see how the fees are structured so the exchanges make money. The rebate is always a little less then the charge going the other way.
It's important to note which gateways do what when trading, because they affect how things go. For example, if you have mad e adecent profit, and just want to get out out of atrade, but don't want to give up the spread, placing an order on BOSX would be a great choice. Remember, BOSX pays you if you remove liq. so generally, BOSX (and EDGE A, which also pays to remove) gets filled first. It's kind of a way of jumping the line. Let's say there are 1000 shares on NYSE, and a few hundred shares in the other gateways, but only 5 on BOSX, you can place your bid there and almost certainly will get filled before any of the other excahnges do. To do this, you will actually be charge a small fee for adding liquidity, but it's sometimes a good trade off if you've already done well on your trade.
On the other hand, if you don't care about getting filled quick, you can place a bid on the more busy ECN's that pay you to add liquidity. But that has it's pitfalls as well...let's say you place a bid on ARCA (which rebates 0.0023 to AL) then you may get filled, but it is very possible you will only get filled as the level collapses. On the other hand, that level may hold, and because ARCA is among the last filled, you may not get filled at all and then the price starts to move up.
What is your situation? ECN fees are only relevent to you if you are directly participating in the market. If you are just using a retail broker, none of this will matter to you.