Two things I take away from this 1) Cool use of infographic :) 2) The little dots represent price changes, not trades. FWIW, some more context around this wo

Two things I take away from this 1) Cool use of infographic :) 2) The little dots represent price changes, not trades. FWIW, some more context around this would be- All the major exchanges stream their best prices to all the other exchanges. This is required because US exchanges must execute trades at the National Best Bid or Offer, or NBBO [1]. So how do you track the NBBO. In theory, by having all the exchanges send their best bids and offers to a central Securities Information Processor, or SIP (the 12:00 box) which then disseminates them (which you can see by the waves of stuff it sends out) In practice, it's slow to go through the SIP on every price movement and the exchanges want to have the best possible information, so the exchanges mostly stream prices directly from the other exchanges (hence the fanout effect on every price movement) Most of these prices movements don't result in trades, they just represent somebody entering or leaving the market at the BBO. This feels like a distinction that could have been made better, rather than just saying "yeah, this stuff's complicated." [1] http://en.wikipedia.org/wiki/Regulation_NMS http://en.wikipedia.org/wiki/Regulation_NMS edit: formatting / citing