When I said that I found the obsession with MM activity amusing, it was more in reference to posters who are less sophisticated than you seem. Most people who post things like "GSCO is on the ask, they must have some stock to unload" don't have the first clue about how and why they can be wrong. My point was that MM activity--at least the way I trade, and I assume the way others trade at the best dealers--is almost ALWAYS more obtuse than you might think. Your point about instinet is a good one. If I am trying to buy a stock that is not really moving, I will NEVER preference another MM or even go high bid, since my firm is seen as a power by daytraders and other MM's; it would be self-defeating and I would never get anything done at the price I wanted. Instead, I will use INCA to go high bid; sometimes I will even go low offer in an attempt to get others to SELL to me. This is just ONE technique I use to buy or sell stock at the price I want....there are others. Also, INCA volumes are indeed counted towards a firm's trading volume.