Quote from d138:
Bobby you are wrong. You are blaming ELPs without understanding what has happened. ELP was not a seller for this trade, but rather a buyer!
You was the seller at 47.09, then somebody else send a sell order for 9k shares at 47.09 and market it ROUZ. This routing instruction means "if you can't match my order on the book, route it to ELP (an possible other destinations)". It is available to EVERYBODY, not to a "special group".
Certainly this order could not be filled at the book since it was a sell at the offer, so it went to ELPs and one of them decided to fill it.
What is wrong with it?