When bitcoin rises, the altcoins keep the price and if when the bitcoin falls the altcoins fall even more. Why do altcoins usually follow bitcoin?
that's the great thing about bitcoin which can move the price up and down the price of other altcoins, but not all altcoins follow the up/down price of bitcoin, sometimes when bitcoin lowers the price there are altcoins that will increase the price, so don't be surprised for example bitcoin price movements are followed by many other altcoins .