Nobel Prize-winning economist Robert Shiller told CNBC on Wednesday he's thinking about shifting his personal money away from U.S. stocks.

The Yale University professor said on "Squawk Box" he has about half his portfolio in stocks. "I'm thinking about getting out of the United States somewhat. Europe is so much cheaper."

Citing moves he's already made, Shiller said, "What I have done is I've invested in Italy indexes, Spain index."

The stunningly low long-term interest rates are pushing U.S. stocks higher, he said. "You look at the major asset classes, they tend to be pricey."

Read More



The solution, Shiller said, is to save more. That's the conclusion of his third edition of his book "Irrational Exuberance."

"Retirement will be difficult if you don't save more," he warned. "I don't think people have reached that state of mind yet."

On housing, the co-founder of the Case-Shiller Home Price Index said he's concerned that the run in recent years may not continue. "We've seen a big increase in home prices since 2012, and I won't bet on that continuing."



"Home prices are ... at about the right level based on history. So may be they won't go anywhere in the near future," he added.



Read MoreCramer: The secret behind skyrocketing stocks

