What started the mortgage defaults though ? (And, also, couldn't cheap oil have maybe helped with the overbuilding of houses in the first place ?)

> What started the mortgage defaults though?

Good old-fashioned fraud. Oil prices had nothing to do with it.

Source: acquaintance who spent three years in court testifying about the rampant fraud in the mortgage industry. He worked for an investment bank which is no longer with us.

I'm well aware of the structural fraud. My point is that the reason that the bubble popped at that point (and not some years later) were the skyrocketing oil prices, themselves a consequence of (conventional) peak oil.

But I guess that it's a bit academical, as that bubble would have popped soon enough anyway...