I thought it was bitcoin. But that's just my opinion because most people who know altcoins are already familiar with bitcoin. So I think bitcoin controls the market. Altcoins also can actually control the market. But I do not see it completely. I only see it in bitcoin and altcoins tend to follow the movement of bitcoin. So bitcoin is controlling the market. That's just my opinion.
Bitcoin is more likely the king of cryptocurrency so it will control mostly all the altcoins, usually the price of Bitcoin and Altcoin are opposite , If Bitcoin is up , altcoin's price will be down .
And rarely, when Bitcoin is down , every Altcoin is down also, that means the market is being swallowed by whales and sharks.