From the last 10-Q, there are 629 million potentially dilutive securities; "C" Preferred, options, warrants, convertible notes. Let's eliminate the options and warrants since those are close to 100% insider held. That leaves 218 million from Preferred and Notes.
It seems likely that a chunk of the 57 million short position is hedging related to the Preferred and Notes. That makes a hell of a lot more sense than believing all 57 million are speculative shorting of a $0.28 binary event OTC biotech.
That logic is uncomfortable two different ways for nwbo zealots:
1) It means that much of the short interest is "friendlies" hedging rather than nefarious forces.
2) It means there is no short squeeze potential. A convertible note holder can convert and deliver those shares rather than being forced to buy in the market.