Yale economist Robert Shiller just won a Nobel prize for his research showing that markets don't always behave rationally.
That thinking helped him accurately predict the stock market bubble of the late 1990s and the housing bubble of the mid-2000s.
So where does he see bubbles brewing now?
"I think there are property bubbles in many parts of the world," he told CNN Money
The S&P/Case-Shiller Index of home prices for 20 major cities (partly named after Robert Shiller) soared 12.4 percent in the U.S. during the year through July.
But it's not just the U.S. where house values are soaring. "Home prices in Rio de Janeiro have doubled in the last five years," Shiller said.
"That looks like a bubble. When I met people there and talked to them, they didn’t think it was a bubble. They had a story to explain it. That looks familiar to me."
Shiller sees property bubbles in "maybe 10 to 15 places scattered all over the world. But they're not everywhere, because human beings have different opinions in different places."
There is talk that the United Kingdom might be in a housing bubble, but John Cunliffe, the Bank of England's incoming deputy governor for financial stability, says no. Still, he doesn't rule out that one might occur.
"If I thought a housing bubble was there, or if things in the housing market were causing risks to build up in the financial sector, then we would want to use . . . tools" to combat it, he said, according to The Wall Street Journal
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