Why BTC is up and alts are down because people are crazy about to buy BCC .
people are selling alts in loss and buying BTC thinking they will get BCC after split. In my opinion this is stupid move.
After Segwit, you will never see alts at these prices.
Don't be stupid, don't sell alts bcs BCC will be sold out fast and it will worth $10-$100 and that is nothing ( 2-4%)profit but from alts you can make 100% easily in 7-15 days. Choice is your but think twice before selling your alts!
So just HOLD your alts and wait for coming 2 weeks then see you will make huge profit .