Quote from local_crusher:
I would really like an IB rep to give an answer to this question _finally_.
The issue has been discussed extensively here in the past - but no statement from IB.
The outcome was, that IdealPro behaves like a true ECN 98% of the time.
However, it appears that liq providers have the "opportunity" to back away sometimes or to add a "confirm before execute" flag to a bid/ask quote.
I am not sure about this - just observations.
Unfortunately, as we all know, these situations will likely occurr when you need your fill most.