Why is the number of shares bought and sold on a given day not the same? Shouldn't there be an equal number of buys to sells?

  • Where are you getting these figures from? Exchanges provide only volume. It may be that your platform tries to guess based on how many fills it saw on a bid vs ask but that's not accurate -- think market moves to fill a limit order. – TainToTain Feb 11 at 19:46

Market-makers buy at the Bid price and sell at the Ask price. That's the side of the trade not counted. Investors that sell at the Bid price and that buy at the Ask price represent the fundamental demand.

Here are a couple of links:



But a market-maker buys at the Bid and sells at the Ask:


A market-maker does not add to sell volume at the Bid and does not add to buy volume at the Ask.

Also the net long or short of futures and options positions is widely reported and here is an example report:

https://www.cftc.gov/dea/options/other_lof.htm .

  • They are indeed counted as part of the volume. Exchanges don't know who putting in a bid or offer to make a market versus who's trading for a traditional position, nor do they care. It's for this reason that there is no separate figure for number of shares "bought" and number "sold". Some platforms try to guess by saying that an execution on the bid is a sell order but it could be a buy being filled at a limit. – TainToTain Feb 11 at 19:45
  • I added some linked sources to the post. – S Spring Feb 11 at 20:57
  • Thanks for adding context. The Zacks article refers to "sell volume" as the volume that occurred at the bid. But that doesn't mean it was someone's (as opposed to a MM's) sell order. If you want to define "sell volume" as volume filled at the bid, that is fine but please leave out the part about MMs. Second, one should be careful not to confuse net position size with volume. The CFTC net position size report shows aggressive position size of its members accounts. – TainToTain Feb 11 at 22:46
  • I meant "aggregate position size", not "aggressive". Can't edit anymore. – TainToTain Feb 11 at 23:02

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