“In a “naked” short sale, the seller does not borrow or arrange to borrow the securities in time to make delivery to the buyer within the standard three-day settlement period.[3] As a result, the seller fails to deliver securities to the buyer when delivery is due ( known as a “failure to deliver” or “fail” ).”

https://www.sec.gov/investor/pubs/regsho.htm

According to the SEC, only 25,662 shares were failure-to-deliver as of October 31. That's a measly 0.018% of the outstanding shares.

20171031|45782D100|IPIX|25662|INNOVATION PHARMACEU|0.79

https://www.sec.gov/data/foiadocsfailsdatahtm