The market is being controlled mainly by,the law of demand and supply and also news relative to cryptocurrency,which migth be for or against the price of bitcoin,the whales in the space also has some level of influence on the market trend.
Just remember bitcoin is volatile and people don't care about it all the want profit if the bitcoin become controllable then we can't make profits.
Other than demand and supply, it is the whales which mainly control the market. To be able to control the market, you need to have a big portion of the coins and whales surely have them.
Well I believe most of the times this sell and buy are even controlled by these whales. They mostly know the mentality of customers and users that are always investing in bitcoin. They see it, analyze and then decide upon it. They better know how to make market unstable so that people start selling and on the same time this market should be attractive for all buyers too.