The explanation I've received from FINRA is that the "daily short sales report" shows trades that were between different brokerages and it can't be settled for several days so the trades show up short. In other words, if a trade between two parties takes place and they both use the same broker, the trade is cleared immediately, the same day. If a trade takes place between two parties that both use different brokers, each broker must lend shares until the trade is cleared between the brokers and the trade shows up as "short" for that day.
However, there is a major disconnect with the accuracy of their explanation. If you look at virtually every OTC or Pinkie trading, the daily short numbers are huge which is the case with SIOR. Check some out, you'll see very large numbers. However, if you look at most name brand firms trading, you'll see virtually no daily shorts reported. Type MS*T the software giant, for example and check the past several weeks, no daily shorts:
SIOR shows up under ORF. The same info provided here is simply pulled from this report and re-reported here at ShortSellingReport, which gives several weeks of data:
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