As chance would have it I just got a call from Schwab Pinnacle services (checking in) and I asked the question about a high sell, good till cancelled order locking up inventory from short sellers.
The rep said that action did indeed remove the shares from the prospective available inventory that could be lent to the shorts.
He checked on CYDY and said there is essentially no inventory available presently to short the stock with, a few (very limited) shares were available, if a person was willing to pay a 61% premium.
Of course that doesn't mean there aren't existing short positions established, just that there's nothing currently available to establish a new short position with.
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