bitcoin can not be controlled, to my knowledge the users of bitcoin itself yuang determine its market price, remember the law of economics more and more demand then prices will go up so it looks like from bitcoin trading system, and therefore its price is always change at any time
Bitcoin can be controlled by the miners. Have you never heard of a 51% attack?
Some pools have come close, back in 2014, I think. Chances of that happening now are lower, but more competion among miners is a good thing.
In terms of the Bitcoin price, control over the price is pretty hard to achieve, I think.
But I guess it's not impossible since the marketcap is still fairly low in the grand scheme of things.