“Whereas the term “short volume” measures the number of shares that have been shorted over a given period of time”
That is not quite correct. Short volume is merely a mark of ownership on the first leg of a transaction. For example riskless principle transactions are all marked short and show up as short volume even though they are all long transactions and create NO short interest.
Short volume is quite meaningless and has no discernible relationship to the amount of short interest which is the important number and only disclosed by FINRA once every two weeks.
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