As BTC hits those new highs, other cryptos are suffering from the trade off. ETH looked like it was on a good run, but it seems that active traders are selling off their ETH to jump on to BTC and see how far it goes above $4000. It's a crazy time, and maybe their timing is off as the $4000 level seems to just be forming a support/resistance level but hey, to each his own.
See how ETHBTC reverses whenever BTC dips (and people trade to buy in to take advantage of the low prices) or when it seems poised to rally (and people try to jump on the wagon).
Looks like ETH might try to find $265-$280 again before trying to break above $300 and continue a run to $380. I'll probably see how that dagger falls first (maybe as low as $215-$220) before I try to see if that rally resumes.