Based upon the historic performance of REITs, there's a lot of upside left in the current rally, said Brad Case, vice president for research and industry information for NAREIT. "What we've seen in the past is that REIT recoveries turn into bull markets that average more than seven years each," he said. "In the last two bull markets, both of them lasted more than seven years. ... The current bull market leaves REITs quite a bit of room to grow."