For me YES, there are many big people behind this manipulation. Specially those people that is really rich, and planning to start to invest in cryptocurrencies. I really believe that manipulation of the price of Bitcoin still effective but it will not be effective forever, bitcoin will become fully decentralized soon.
But I think that now it is becoming difficult for them to manipulate the bitcoin price. I think that the current decrease in bitcoin price is only because of some bad news in the market and hopefully very soon bitcoin price will reach too much good.