correct. the part that seems to evade people's mental model of this process is that the exchanges know which orders in the book are theirs, but the customers d

correct. the part that seems to evade people's mental model of this process is that the exchanges know which orders in the book are theirs, but the customers do not, so there's no risk whatsoever of the exchange filling an order that works against their balance sheet. it all looks perfectly organic from the outside.