It is not possible if only one person can manipulate or influence the price, for sure it is an organization, but again, those whales (if true) are good guys as they don't manipulate the price, meaning they have so much bitcoin that they can influence the price but they aren't doing it. In contrast to altcoins, once you have a large portion of it, which we can easily obtain on presale, or if it is new, the price will drop when you begin selling your coins.
It is possible if a person holds a significant amount of Bitcoin, he can have the potential to influence the price of Bitcoin. Since they hold large amounts of Bitcoin, they can sell large amounts of Bitcoin which can cause a significant price of fluctuation. The good thing is whales can act individually and may have different positions that sometimes contradict each other.
Even though whales have the potential to influence the market it isn't accurate to say that they control the Bitcoin price because there are other factors that affect the Bitcoin price.