Let's assume a third-party manipulator (i.e. they can't print new Tether).
To make this economical, they would need an in with at least one exchange. Their trades on this venue (let's call it ShadyBit) would be free, or close to it. This is where the majority of their wash trades happen. If one naïvely averages volume across the market, this will do the trick.
But the jig will fall apart if another exchange starts sharply diverging. So you set up sock puppet accounts there to soak up excess demand. As long as you keep the confidence game balanced, there shouldn't be too many people looking to sell at unusually low prices.
In the meantime, you can continue using your inflated-value tokens as collateral for borrowing or to buy appreciating assets or to sell or whatnot.
You’re responding to an allegation of fabricated volumes by quoting volumes.
And its not like USD-USDT hasn't become uncoupled before. It's been as low as .7 in the past.
You're describing a shallow order book. This happens quite frequently in less-liquid markets. The transaction signature of a shallow order book is large orders prompting a pause in trading, as the order book is drained and refilled.
Contrast that to a hyper-liquid market like that for on-the-run Treasuries. You'll have a mix of price and time preferences, with some people wanting immediacy and others willing to provide it for a discount/premium.
The presence of continuous, non-volatile trading--particularly on the downticks, given a pegged asset--is very unusual. Enough so that I've never seen anything like it before in a properly-functioning market. Which is suspicious.
Former algorithmic trader. You're right–the ceiling isn't particularly unusual. That prices never cross through is weird, but not inexplicable.
What is inexplicable is the downtick inelasticity. Large sell orders should burn through more book than small orders. As the top of the order book is burned, lower bids are revealed. Even in the presence of lots of arbitrageurs, there will be transactions at those newly-revealed lows.
That isn't happening. Instead we see a stable harmonic evocative of wash trading.