I have a question for you... If I'm joing the big/offer how do I get filled? Is it using a FIFO algo to get filled? Or being a retail customer do I simply get screwed? Are there traders with special privaledges in terms of priority of getting filled? I say this because I feel Im always last in line to get filled. I'll always get filled right when the level is about to print through. john
Which instrument? If US equities, see the following for a really confusing discussion of some of the relevant points: http://www.elitetrader.com/vb/showthread.php?s=&threadid=208413
due to order internalization if you place an order on an exchange you're behind the real players but may be in front of some retail.
Price then time priority (FIFO). Visible orders get filled before hidden. (Although some new exchanges are going to try Price/Size priority.)