I am brand new to IB and it seems that you can trade with any ECN, but is there anyway to preference a market maker on selectnet? I am able to get Level II info elsewhere. Also if you place a market buy order for 1000 shares at Best, and lets say Island has the best offering for 100 shares, then Arca for 100 shares, and so on so it would take 6 tickets to complete the order, is this how IB works? Does it just take each offering in order to complete the order with regard to size offered? Thanks
IB does the preferencing internally based on a number of factors - including the prior experience with previous market makers. It does not allow individual users preference a particular market maker. The NASDAQ feed uses selectnet. BestEx will attempt to get the best prices for you order. Thus if you submit buy 1000 and the best prices are scattered amongst a bunch of ECN's, you will get filled in a few places.