REITs' prospects are tied to the overall economy in the U.S., says Sam Zell, chairman of Equity Group Investments. "REITs will grow commensurate with the country. If the country isn't growing, we don't need any more real estate," he said. At the same time, supply and demand of commercial real estate will also have an impact, he says. The good news is there hasn't been much construction for the past 2 1/2 years, which is low by historical standards. "When there is oversupply, real estate always suffers," Zell says.