What is the current state of the investor market?

Spent some time today looking about a dozen condo units in Midtown that were offered both for sale and for rent. Simple annual returns (rent less taxes less common charges divided by asking prices) showed all were under 2.0% (except for one unit at 2.4% which was offered for rent furnished). Where do people think the investor market is headed? Are sub-2% returns sustainable or just a sign that the market is not in balance? I wonder just how big the investor market is in Manhattan. Anyone have good statistics on this market such as the % of existing condo units that are tenant occupied? My guess is that investor units as a % of the overall market has grown substantially in the last 10 years which is a risk factor for home buyers that is well under the radar for most observers.