Who controls the course of Bitcoin?
The whole idea of bitcoin is NOBODY to control it.The currency should be fully decentralized and anonymous.
The bitcoin "course" is controled by supply and demand like every currency.
If you are asking who is holding the largest amount of btc,i don`t know...
Literally, bitcoin was controlled by the owner who has the possession on it. If you own coins then you have controlled of it. If you put it an exchange then you don't have control over it. But in general as a whole, no main institutions holds and control bitcoin overall.