This was done long ago:
Control the information, control the response, control the public.
It is easy to find a list/chart of all media ownership (print, television, radio, internet) that shows most are controlled under 6 (now 5) major conglomerates.
This chart is now 10 years old, and many, many mergers have occured since then:
http://adage.com/images/random/mediafamilytree07.pdf