Is residential multi-family on the radar of institutional buyers?

[Wayne Marques]

We all know that institutional investors have always targeted large commercial residential assets and, more recently, they have been increasing their rate of acquisition of single family homes.  My question is, why haven't I heard of them acquiring, or building, portfolios of residential multi-family homes?  I know some investors prefer single family over small multi-families, so I would assume there might be institutions that prefer one strategy over the other.  

Is it already happening but we generally only hear of single family acquisitions?   Why wouldn't they target the small multi's?  Is this on the horizon?   Or is there something keeping them from buying?