Can anyone give information on the relatively new market maker "NSX" that seems to be on the inside market in so many nasdaq stocks in recent weeks? To me, NSX seems to put in tons of orders, showing bids/offers of fluctuating size and not printing most of their quotes. Who are these guys and why, all of a sudden, are they in so many stocks? Similarly, what's up with "edgx" everywhere now? Anyone else finding trading with their quotes a bit unsmooth?