One single person/entity on Bitfinex has controlled the entire bitcoin market from $200 till now.  The only time that person/entity wasn't controlling the market was when the price briefly went higher on Bitstamp and GDAX when it was like $2700 recently.  Some people liked to make believe exchanges like Huobi controlled the market for a while, but they just use fake volume to paint the tape and they could never move the market higher than exchanges like Finex allowed.

The rare exception to this rule might be that one enormous OKcoin short squeeze, but it might be the same entity from Bitfinex squeezing OKcoin shorters too.  Whether the price of bitcoin is high or low, the price is always based on a tiny handful of fraudulent actors and a few crooked exchanges.  The sole actor controlling the market is just as likely to be the exchange owner himself as an external entity as well.  We've already seen this precedent with Gox and it probably still continues to this day.

Poloniex is another fishy example.  It used to be where 2000 BTC volume for a coin per day was huge, then overnight suddenly every coin has 50,000 BTC volume for no reason.  I have a feeling there is something not good going on behind the scenes of that.