Some will say that those "Whales" are the one who controlling the stability of the market. But I don't think so, they just have a big impact on the value of the market because they invested a lot of money but they did not totally take control of it.
They may be just some of all those who invest a large amount and make a price change if they make a withdrawal or sale transaction. Maybe so.
They are the one who owning a lot of coins and they could sell whatever price they want, but cause of that lead to the shortage of coins on the market and the price will be pushed up.