PORTLAND -- The price of a home in Portland has risen by 12.5 percent over the last year, according to the S&P/Case-Shiller Home Price Indices released Tuesday.
And it's not just a Portland trend. U.S. single-family home prices in May saw the biggest annual jump since 2006, the survey showed.
The index of 20 metropolitan areas gained 1 percent on a seasonally adjusted basis, shy of economists' forecast for a 1.5 percent increase. That marked a slower pace from April's 1.7 percent rise. On a non-adjusted basis, prices rose 2.4 percent.
Interactive: Home prices jump 12.2 percent
Compared to May 2012, prices also fell short of expectations, rising 12.2 percent from a year earlier. Still, it was the biggest annual gain since March 2006, matching a record set in April.
The report was unlikely to alter economists' views that the housing sector continues to recover, making it a bright spot for the economy.
The cities that bubbled in the past are bubbling again, Robert Shiller, economist and co-founder of the S&P/Case-Shiller Home Price Index, told Squawk on the Street on Tuesday.
Ten cities--Portland, Seattle, Chicago, Denver, Detroit, Las Vegas, Miami, New York, Phoenix and Tampa--showed signs of acceleration. Portland prices rose 2.1 percent from March to April and 2.2 percent from April to May.
To me, it seems to be at least partly psychological. They've seen it before and they're ready for it again, Shiller said. It seems like California has historically been the most bubbly state in the country and it continues.
He said that the new factor emerging in the numbers is the effect of institutional investors on home prices. They've learned about momentum and they're saying 'hey, this is it.' The housing market is showing a lot of upward momentum. And you know, I think they're probably right, at least for the short term.
For a flipper who can get out in about a year, it seems to be a fairly safe bet, he added.
All 20 cities rose on a yearly basis, led by a 24.5 percent surge in San Francisco.