Here's the best I can come up with:
Quote:
SHORTS data explained by FINRA...phone call 3 minutes ago i spoke to FINRA regarding their daily SHO list which seems to show 30-70 % off all the volume in thousands of stocks as 'short sales'. they explained the 2 factors which tend to inflate the short sale data beyond what is normally considered a short sale, i.e. a person or firm borrowing shares which are then sold.
1. all marketmaker sells to buyers for which the MM doesnt at that moment possess the stock would go onto the list. the shorts data is sent to SEC at time of execution, so during the course of a day, a MM may trade 20M shares of company xyz, of which 10M of those shares were initiated as short sales and the other 10M were buys to cover those shorts. despite the fact that their net position at the end of the day is flat, the data would show 10M shares as having been short sales.
this applies even to grey sheet stocks. despite the fact there is no MM making bids and asks, MM's can and do call around to other MM's to find willing sellers to match buy orders and vice-versa.
2. Trades in certain classes of
securities, such as Rule 144A securities, are
reported to the ORF, but not disseminated. Nondisseminated
securities will not be included in
either the daily short sale volume file or the
monthly short sale transaction file.
FINRA: they confirmed that in order to ascertain the true "open short" position one should look at the bi-monthly short report. it was also stated that any of the daily shorts which were not delivered within the prescribed time would definitely end up on the FTD list.
News 
Market Data 
Discover 
