Quote from danger66:
Nick, we are not trading on CX yet, despite having all our agreements with a few brokers in place. The set up we have at another firm is a rig similar to CX in principle, where you have a few banks posting liquidity. The greatest size we did there was $3.5 million a clip before we got shut down on 11/29/06. We made good money despite the fact that we were getting over 65% of our trades rejected. Some executions were at the price clicked, but most where within 2-pips from the market price (as specified by us). It takes time for the order to reach its destination after you press buy or sell. If this is being done on a fast market, you can't expect the price to be the same even 100ms later.