... magically one millions Ardor appear into the sellbook, bringing the buy value down.
I see some smooth uptrends and then someone would take one million Ardor out of nowhere to sell them and keep everything. It is clearly an unethical move and I hope we get answers about that.
You should also consider arbitrage with NXT AE orderbook.
Lots of trading done there at prices like 1.5NXT - 1.75NXT