Some credit them with saving the housing market. Others blame them for taking advantage of a crisis and bullying real homebuyers out of the American Dream.

Whatever their role, large institutional investors put a floor on home prices during the housing crash by buying up thousands of distressed, single-family homes. Now they are slowing their purchases, but not exactly getting out of the trade. They are holding on to what is becoming an increasingly lucrative asset: The single-family rental home.