Sometime it can be manipulated, and most of whales are manipulating the cryptocurrency by the price, but we should to be aware and should be stronger in take decision because it can be a trap for us before buy or sell any coins.
It will not work for the whales of we will be determined and not to sell, they just do this for their own betterment, most of time new users get trapped by them but those who knows will never sell their bitcoin to help them manipulate the market, actually they do this pre planned for better low price bitcoin, they sell high amount of bitcoin in market so price gets down for higher supply them those greedy and clever whales buy double amount of bitcoin to increase their income.
It is interesting that even before entering the market the newcomers are educating themselves fully and when they enter the market they still don't know when the manipulation occurs. Bitcoin has become so popular and because of that popularity, many newcomers want it because of its volatility and because of the mystery future growth. When the observers saw the last year growth all of a sudden every one of these same observers is entering the market which isn't in fully manipulated but in most cases it is. All are hoping for easy money but instead of reacting to the mentioned manipulation they should just ignore it! But for the ignorant ones ignoring is not possible because in the moment of the well-organized manipulation they don't even know that it is already happening.