Fifteen years after buying the rest of Charles E. Smith Commercial Realty to expand beyond its New York stronghold and become one of the largest office building owners in the metropolitan Washington area, Vornado Realty Trust (NYSE: VNO) announced it plans to spin-off its Vornado/Charles E. Smith affiliate as a separate business.

And while Vornado has signalled the move for some time, combining the spin-off with The JBG Companies, another major…