hi there, lets start a discussion on the pros/cons of various ECNs. Long time ago, I was always using Island, so just migrated to NASDAQ after the acquisition and always been using NASDAQ from there. I am not familiar with other ECNs but think that I should consider all of them to optimize my trades and understanding of the market. How are the fees of the various ECNs? their liquidities/fills? speeds? etc? Does anyone have a brief idea of the ECN market shares?