Equity Residential (EQR) is well poised to gain from its high-quality, diversified portfolio in markets with an affluent tenant base. Healthy demand for rental units, strategic portfolio repositioning and technological enhancements are likely to aid the company.However, the elevated supply of residential rental units in some of its markets is a key concern. Also, high-interest expenses add to its woes.Over the past year, shares of this residential REIT, carrying a Zacks Rank #3 (Hold), have gained 15.7%, ou ...