<< that's not what I said. What I mean is for every sell there is a buyer. No? >>
No, that is a common misconception.
When retail (ie, the general public) buys or sells, they are trading with a Market Maker. That is why there is a spread. In general, retail buys at the ask and sells at the bid. The general public doesn't trade directly between each other.
Markets where the general public trades between each other are called Matched Markets. The Grey / Expert market are matched markets (where there are no Market Makers.
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