Post Properties Inc. shares rose the most in seven years after Mid-America Apartment Communities Inc. agreed to buy the real estate investment trust for about $3.9 billion, forming a company with about 105,000 multifamily units amid rising demand for rental housing.

Post Properties investors will get 0.71 of a Mid-America share for each of their shares, the companies said in a statement Monday. That equals about $72.53 a share, or a 17 percent premium, based on Friday’s closing prices. Annual gross synergies from the acquisition are expected to be about $20 million, the REITs said…

Post Properties Surges on $3.9 Billion Deal With Mid-America