Short covering, most likely. In theory, one would think a shorter would just ride the stock through the cancellation date and make a guaranteed 100% return. But in practice, it doesn't work that way.
Any shorter has to borrow the stock from someone who is long. That gets extremely difficult when a company has been delisted from the Exchange. Most of the previously available shares were lent by institutional holders, but they absolutely know how to read SEC filings and know the stock is going to be cancelled. Most of them have already sold their entire long positions and salvaged whatever money they can get. In those cases, the person who borrowed the stock from the holder who is selling has to either find a new lender or cover their position in order to give the stock back to the original lender. That is almost certainly what is happening now.
There is also the problem of maintenance fees. Borrowing stock to sell short is not free. Very liquid stock has a low fee, while illiquid stock, like WTSLQ, has very high fees. The fees vary by day, and with the stock being cancelled next week, anyone still long is almost certainly demanding massive fees to lend. It likely makes more sense to close any short position now, especially since the tax situation can be complicated by the cancellation on the last day of the year.
And then there is the case of those people who either don't bother to read the SEC filings, or choose to ignore them. And those that listen to such people. They might be buying somehow thinking the stock is cheap and will rebound. It isn't, and won't.
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