Real Estate Investment Trusts have been outperforming the Standards & Poor’s 500 Index, but they are starting to overheat as investors pile in. Per Business Insider:

"Most REITs in our coverage have dividend yields well below their historical norms," says Todd Lukasik, a senior equity analyst at Morningstar.

"These valuations aren't sustainable," says Geoffrey Dancey, a portfolio manager at Cutler Capital Management LLC in Worcester, Mass. "And they can lead to lower stock prices down the road, he adds, translating into losses."