>>Why would they do this? Either Primex is cutting them in on some revenue or they are trying to avoid ECN fees.<< Agree 100% with AAA on this one. IB used to have the fastest and best executions out there. Unless IB is getting kickbacks for routing through PRIMEX or trying to avoid ECN fees, it simply makes no sense to change the execution algorithm. If IB is getting kickbacks from PRIMEX, why not just route to market makers NITE or HRZG (as does Ameritrade, ETRADE and the like) too? IB can probably get a higher percentage than might be paid by PRIMEX and the executions will be just as lousy. IB is going down the drain, in my opinion. Unless this PRIMEX matter is resolved soon, I'm transferring my funds to Tradestation and just trade thru them. Commissions may be a bit higher, but the higher quality executions certainly makes up for that.