Law of supply and demand
Some rumors like china thingy
Some exchange in structure of bitcoin
like hard fork. Soft fork. And segwit etc.
That is what I see how bitcoin affected the price
But even if that affects a lot bitcoin will recover after time.
Hope these year it will hit the 10,000 USD mark up speculated price
Sure, all these things together affect Bitcoin price. However, today there are more very positive factors that will make the king of crypto growing again.