It seems that the Nasdaq and NYSE are becoming more like each other, but that, as should be no surprise, the changes are uneven and sometimes uncomfortable, especially when they make previously effective or efficient trading tactics more difficult. It's possible that, at the same time that the various financial markets become more uniform, trading in particular stocks, especially the "top tradables," will become more variegated - sometimes more like the "old Nasdaq," sometimes more NYSE-ish, sometimes combining the best of both, sometimes the worst. Initiatives by ARCA and AMEX seem to represent two opposite sides of the process, and it's both typical and ironic that the interaction between the two in fast markets on Nasdaq stocks can be highly disadvantageous to the trader who allows it to take place. The experience of having an ARCA order trapped by AMEX at one price extreme, then left unexecuted while the market moves away, is one that I intend never to undergo again. It's not hard to imagine complications of this and other types continuing to develop and even to proliferate, offering both opportunities and obstacles often at the same time.