It's amazing to find out how many people were involved at manipulating LIBOR rates and all of them kept it a secret for years. I don't think it would be that difficult to control real estate inventory either and keep it a secret.
What happened this year with inventory might have been a manipulation. Inventory dropped at a time when it should have been rising. If the banks decided to limit the inventory and gotten top producing brokers (5% of brokers) to do the same, the effect on inventory would have been significant.
BTW, I made a comment about this early in the year when I thought that inventory was acting strange.
OR all of this was a function of interest rates dropping significantly.