Since it was feared that hard fork is going to happen and a a result of it,bitcoin price might get crashed,most sold their bitcoins in panic.Since altcoin price is valued in bitcoin price,many sold their altcoins also and this lead to fall in altcoin price also.But now,hard fork has happened and still bitcoin price is normal at $2700 and so,following it,altcoins prices would also increase here after.
Eventually everything will be back to normal ,some alts may pump or lowered just in minimal amount. It just shows that even there are hard forks again to happen, btc is strong enough now to faced it and can stand still no matter what.