It appears that Coinmarketcap are masking ETC volume on Huobi and OK Coin.
I have tried to contact them to get it sorted but all efforts have failed. It seems they took a back hander from ETH maxi to hide the volume on ETC trading on those major Chinese Exchanges.
This sort of behavior been going on for a long time. Before coinmarketcap masked Korean exchange volume on the peak pumps on ETC.
Coinmarketcap are gangsters.
you shouldn't take volume seriously with crypto as most are fake. coinmarketcap is a known eth pump site and is eth bagholder.