nitro,
NX - I assume you mean NYSE direct. IB's internal NYSE routing should direct orders to NX if they are eligable. I'm not sure of the specifics.
I was of the understanding that if you select NYSE you should get NYSE. If not, send a note to IB Mgmt asking for an explanation.
I'll explain the TMBR routing again in the attempt to emphasize that it only provides better executions.
The Timber Hill prop side trades on average over 100 million shares of NYSE stock per week. Its trading model has a given market for all of the stocks it trades at any given time. These prices are naturally constantly changing.
IB's SMART routing will take the bid/ask prices from the various exchanges and create the best national market. If TMBR's internal price is equal to or better than the other exchanges, the order will be routed to TMBR. As long as speed and price are your main concerns, you should not care if you get filled at ISLD, NYSE, TMBR or elsewhere. Naturally since the TMBR orders can be matched internally, execution speed and confirmation will be faster. It is a win/win situation. You get an immediate and faster execution than otherwise possible while IB saves on exchange fees. TMBR as a client of IB receives the same benefit of other clients. Sure TMBR is hoping to profit from your trades. But then again, what do think the specialist or the other side of your order is doing.
Some other key points I'm pulling from our web site:
Question: Will Timber Hill ever hold on to my order if it is routed to the Timber Hill Automatic Execution Service?
No. All orders routed by IB to Timber Hill will be immediately automatically executed, with no delay and no human intervention. IB will not route any orders to Timber Hill that are not immediately executable. Thus, Timber Hill will not handle or represent non-marketable limit orders.
Question: Can Timber Hill "peek" at my orders and trade ahead of me before my order is executed?
No. Strict procedures prevent disclosure of your orders prior to their automatic execution by Timber Hill. Again, unlike some other specialists and market makers, with the Timber Hill Automatic Execution service, you will see your orders being executed immediately.
I understand the concern from some clients but in reality the TMBR route is simply a competitve advantage. For more info refer to:
http://www.interactivebrokers.com/html/retailAccount/faq/auto_exec_faq.html