Comcast is owned by the following major share holders (names provided by Yahoo! Finance):
Brian Roberts
Ralph Roberts
David Cohen
Stephen Burke
Neil Smit
A majority shareholder is a person or entity that owns more than 50% of a company's outstanding shares. The majority shareholder is often the founder of the company, or in the case of long-established businesses, the founder's descendants.
Comcast founder, Ralph Roberts, died in June 2015. His son, Brian Roberts, now serves as the company's chairman and CEO.
Shareholders have the primary rights but many entities own stock in a large corporation for investment purposes.
Institutional ownership is the amount of of a company’s available stock owned by mutual or pension funds, insurance companies, investment firms, private foundations, endowments or other large entities that manage funds on the behalf of others.
Data provided by NASDAQ.com, see Comcast's list of institutional holders and view the company's ownership summary.