the numbers I have seen suggest that institutional investors own about 500k of the ~100M residential properties in the US. Small investors probably own about 15M in total. Roughly 2M units are for sale, so even if every single institution-owned unit was for sale they wouldn't be able to exert much influence. The fact that this is a big, complex and widely distributed market IS the reason they can't distort it like they do with specific industries in a given geography.