U.S. single-family home prices rose in June, though the pace of gains slowed slightly, a closely watched survey showed on Tuesday.
The S&P/Case Shiller composite index of 20 metropolitan areas rose 0.9 percent on a seasonally adjusted basis. Prices rose 1 percent in May.
On a nonadjusted basis, prices rose 2.2 percent.
Compared to a year earlier, prices were up 12.1 percent, in line with economists' expectations. Prices were up 12.2 percent in the year to May, the biggest gain in more than seven years.
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"Obviously we're in a housing recovery, at least for the short term," said Robert Shiller, Case-Shiller Index co-founder & Yale University professor of economics, told "Squawk on the Street" Tuesday. "Housing is a market with momentum and right now, the momentum is up."
"In the single family realm, I think that there is a chance that there is weakening," Shiller added. "The housing market has gotten very speculative and it goes through big cycles … It's a rollercoaster, that's what these markets have become."
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Shiller said that because of all the speculation in the U.S. housing market, there is an inherent risk of the momentum weakening. The market is driven by "irrational exuberance and that can suddenly change" he explained, and since large investors are looking to buy up homes and flip them, "the market is going to change" when they exit their investments.
The report suggested the housing sector continues to recover despite a recent rise in mortgage costs. Economists have pointed to a stronger housing market as a bright spot in the U.S. economic rebound.
Prices in all 20 cities rose on a yearly basis, led by a 24.9 percent surge in Las Vegas and followed closely by a 24.5 percent gain in San Francisco.
—CNBC contributed to this report.