I checked the loan/mortgage interest rates in China and they are basically the same as the US. So the overnight rate being the 'bank to bank' rate must mean there has been a huge run on Chinese banks and they don't have much money to lend. That doesn't sound good at all.
In absolute terms the Chinese housing bubble is about 20 times bigger than the US housing bubble was.
Don't you mean in relative terms?
No, sales rates exceed occupancy rates by so much that doors and plumbing fixtures are installed by the buyers, if and, when they move in. That in turn means that appliances cannot be moved in without inviting theft and trim and cabinetry should not be installed for fear of vandalism. There were reports of sold out properties with less than 1% occupancy. That was more or less confirmed by a famous case a few years back in which a rather large building with more than 100 units collapsed and one woman died. The building collapse was in full view of an office building housing the office of a non-Chinese news service which is how I heard about it.
I have no idea why or how this is going on. but youtube has worlds without end videos about the ghost buildings, developments and cities if you want to run the numbers yourself.