"It is up 12 percent in the last year. This is a very rapid price increase right now, and I believe that it is accelerated somewhat by the Fed's policy," Shiller said.
China, Brazil, India, Australia, Norway and Belgium, among other countries, were witnessing similar price rises. "There are so many countries that are looking bubbly," he said.
The Fed has held U.S. interest rates near zero since late 2008 and almost quadrupled its balance sheet to about $3.7 trillion through a campaign of bond-buying, or quantitative easing, to hold down long-term borrowing costs.
Placing more emphasis on avoiding asset price bubbles, and financial stability in general, has been a controversial topic for many years in policymaking circles.
Central bankers traditionally try to avoid targeting asset bubbles with a blunt instrument like interest rates. But the severe harm done when a bubble bursts means that, in the United States at least, they are thinking more broadly about the unintended consequences of their monetary policy decisions.
"When asset prices are getting way out of line it should be cause for alarm. The monetary authorities should lean against extreme asset price movements," Shiller said.
The bubbling housing market is not mainly the result of central bank policy, but reflects a shift toward "a more speculative attitude," he said. "We cannot expect monetary policy to cure all of these problems."
Hansen struck a more cautious note. "We often underestimate how much uncertainty there is in terms of our understanding of the economy," he said. "If you pretend that we know more than we do, you are in danger of constructing policies that can be counterproductive."
Different thinking on markets
The Royal Swedish Academy of Sciences said the laureates' insights "provide guidance for the development of theory as well as for professional investment practice."
Fama, tipped as a Nobel winner for many years, has been called the father of modern finance and is well-known for research showing certain groups of stocks tend to outperform over time, and for thinking about markets as efficient.
This view of how assets are priced is at odds with Shiller's belief that investors can fall prey to "Irrational Exuberance," the title of his 2000 book, shortly before the bursting of a global bubble in information technology stocks.