It seems to me Tether is likely behind in holding USD. If someone trades for USDT with BTC then Tether would need to immediately sell the BTC and convert to USD. If time passed and the price dropped then they would need to make up the difference. In an up market they can take advantage and pocket reserves. If this wasn't done during the run up then they could be in trouble. Perhaps we could find out they are only 92% backed. They may be ordered to make up the funding gap by a specific date. Assuming they charge a fee? That would be a way to pay back into the system and wait for the market to go back up.