hacer
Active Member
It is true that every transaction has a buyer and seller, however there is also an initiator of the action. Back in the day when nearly all transactions went through a market maker they could always clearly identify a (public) buyer vs seller. These days it is trickier, but you can still see a transaction that takes place on the bid (or lower) as being initiated by a seller while a transaction that takes place on the ask (or higher) was initiated by a buyer. Without those initiators, the bid and ask would just fluctuate with no transactions. The entities providing bids and offers are essentially saying I will buy or sell if someone else will meet my price while the person who places the market order (or targets the bid or ask) wants to buy (or sell) now. These days there is a lot of pay for order flow where transactions take place between the bid and ask and that makes it more difficult to label the shares traded as having been "buy" or "sell" volume. Finally it has always been more common to measure "up" and "down" volume which is similar too, but not the same as "buyer/seller" initiated volume.Every transaction involves an equal quantity of buying and selling. Put a different way, every purchase of stock requires an equal sale of stock by somebody else. And vice versa.
Volume = buying volume = selling volume.