I guess there is no exact reason why bitcoin price has up and down many times, and it's happening in every day. The altcoin will follow wherever bitcoin moves and many of them still increase even if bitcoin price is down. But some of the altcoins will following bitcoin to get down and waiting for the next moment to increase again. And now, bitcoin price has increased again and the altcoin following to increase too, and we see the market will make another green candle again.