There's a thread on orders submitted before the open on the IB board, in which I tested various combinations of SMART, NYSE, MKT, LMT, DAY, OPG. Basically, for orders for NYSE stocks sent before 09:30, SMART/OPG, NYSE/OPG, NYSE/DAY all send the order to the NYSE, where they will participate in the opening print if otherwise qualified.
SMART/LMT for NYSE stocks placed some period of time before the open will be sent to an ECN immediately (generally INET or ARCA, depending on what's open and other factors). I don't know if they get rerouted to the NYSE as the opening approaches.
Someone else mentioned that IB does, indeed, send OPG orders for Naz stocks to SM, but that the nature of that opening cross is "best efforts" - MMs are not required to fill all opening orders if there is not enough liquidity around and they don't want to provide it.
SMART/LMT for NYSE stocks placed some period of time before the open will be sent to an ECN immediately (generally INET or ARCA, depending on what's open and other factors). I don't know if they get rerouted to the NYSE as the opening approaches.
Someone else mentioned that IB does, indeed, send OPG orders for Naz stocks to SM, but that the nature of that opening cross is "best efforts" - MMs are not required to fill all opening orders if there is not enough liquidity around and they don't want to provide it.