Nobel winner Robert Shiller says there's still a risk of a full-blown bear market

"There is a feeling that the stock market might be due for some deflating now because it's been a long time, and we've seen some hints of it and we haven't seen the real deflation yet," he told CNBC at the World Economic Forum (WEF) in Davos, Switzerland. U.S. stock markets may have recovered slightly from sharp falls at the end of last year, but there's still a risk of a significant downward trend, Robert Shiller, a professor of economics at Yale University and a Nobel laureate, told CNBC Wednesday.