Quote from speculatus:
If a broker sends an order down to an exchange/ECN where the quote is away from NBBO, the order will be rejected (on NSX for example), or a the broker will be charged for a routing fee (there are few exceptions). So it is important for SmartRouter to send an order to the exchange that posted NBBO. The second factor is rebate/liquidity matrix to keep the execution cost low.
NYSE recently lowered it's fees, so now wonder NYSE is often preferred place to trade listed stocks. I trade NYSE listed stocks only and always get instant fills since I always set the destination to NYSE (remember that IB is a member of NYSE, so they must have direct FIX connections to the exchange).
I don't agree with the your first assertion...
That orders "away from the NBBO" are in any way penalized.
The regulation is "best execution"... NOT "best price".
There is NO obligation for any broker to get you the NBBO...
If they can make a case that, overall, your trades are getting "best execution"...
And that case can be made using about a dozen loopholes and exceptions.
IB can easily make a case that SMART, overall, gets the Customer "best executions"...
Regardless of whether any particular trade gets NBBO... or not.
On your 2nd point...
The reason 80% of my SMART Limit Orders go to the NYSE and are executed there...
Is because that is the primary market for most listed stocks...
And that is where you are MOST LIKELY to get an execution.
The NBBO is irrelevant... if no execution.
Actually getting an execution as often as possible...
Is everyone's primary interest.
Many active traders...
Would rather do double the volume at slightly worse prices...
And make more money overall.