Majority Shareholder

A person or conglomerate who owns more than 50% of the outstanding shares of a corporation.

Investopedia Says:
Owning that much of a corporation gives an entity a huge amount of control. The majority shareholder is often the founder of the corporation.

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One of the shareholders who together control more than half the outstanding shares of a corporation. If the ownership is widely scattered and there are no majority shareholders, effective control may be gained with far less than 51% of the outstanding shares. See also Working Control.