OTC stocks don't trade after hours, period. I can tell you with almost 100% surety what that block was. An MM was given a large block of shares to sell during the day, maybe 100 million or 200 million, I don't know. They didn't actually buy the block themselves, but sold from it during the day (think of it as a consignment sale). That T trade was the MM buying the number of shares he actually sold from that block during the day. So, it won't be any surprise if the daily short number is high today, like at least the amount of that after hours block.
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