Alan Greenspan refused to categorise conditions in the US housing market as a bubble when he was chairman of the Fed.
But now he's retired and while plugging his memoirs, he admitted in a TV interview the other day that lots of froth in different parts of the US made up what was, in reality, one giant bubble - similar to the one that went pop in 2001 with the collapse of the dot com shares.
Take a look at this article from The Economist which suggests that there are six countries - Belgium, Britain, Denmark, Greece and Spain - where a housing market crash is even more likely than in the US. In these countries, the article suggests, average house price inflation is 47% above what is justified by fundamentals.
And then look at Asia. In Singapore, property prices have doubled - even tripled in some cases - over the last two years. Speculation reached fever pitch until an increase in government taxes and the global credit crunch brought sanity to the market a few weeks ago. Now there is talk is of another property price collapse similar to the 1997 meltdown.
Then there are the property booms in India and China.
You can argue, as the Asian Development Bank does, that Asian fundamentals are so strong that the continent can ride out a US credit-crunch driven recession.
But what goes up has to eventually, surely, come down and bubbles have historically always gone pop.
And so from this calculate how many polymers and chemicals go into the construction industry - from PVC to formaldehyde - and think of a worst-case scenario for your business. This could be the froth being taken out of the market - meaning property prices falling back to where they should be based on the fundamentals. But as is often the case when sentiment turns bearish, prices could collapse below their real value. Fantastic news for bargain hunters with nerves of steel, but not much use if you're operating a PVC plant.
The global property bubble could pop as early as next year, if the Fed 50 basis point cut and any future measures fail to bring the credit crisis under control.