I think it's worth mentioning that Nasdaq, INCA/ISLD, ARCA/Redi are separate markets. They are competitors in OTC trading. Nas does not operate OTC trading, they are trying to hold on to whatever market share they have using their (ECNs would argue monopolistic) control over the national quote display, and if they can't either shut down the ECNs or get them into the fold, they may continue to lose market share. Hence, a new system - SM! Does it address trader issues such as fragmentation, or lack of liquidity at a price level (by having orders that sweep to other levels)? Not in any way that has not already been addressed by software vendors. Execution software provides auto-route and sweep orders. They are fast, and you don't incur the execution and price (in ECN and/or Nasdaq fees) risk in having an order forwarded around between markets. Regarding ECN and daytrader participation, an official has explicitly stated "This is OUR system", meaning Nas and it's NASD member MMs. What is to stop them from implementing controls to exploit their advantagous position over the ECNs? For Nas, it's good business. But we are dealing with a competitor in, not the owner of - OTC trading. I say we, as DAY-traders who are already subject to the evil eye from some in the industry (and if you are a short seller too, you are doubly scorned - you know you are the reason the market goes down! ) - SHOULD give our allegiance to the market with the lowest costs and best liquidity, exercising our right as customers instead of letting the Nasd decide where we do our business. Then we can erect buildings in Times Square with big video screens for ISLD and ARCA, and let some real competition begin!