its been posted on here or reddit that those are fake numbers cuz no commission trading so people buy/sell to themselves to create fake volume/pump
There were reddit threads about fake Huobi and okcoin trades since 2014. I quoted one comment that compares them to mtgox. There was a reddit thread by an ex-okcoin employee who said they run their own bots to manipulate both volume and price. Those exchanges deny it but I don't believe them, they fake their volume.
https://www.reddit.com/r/BitcoinMarkets/comments/1ub0f0/convince_me_why_huobicom_stats_are_not_fake
https://www.reddit.com/r/BitcoinMarkets/comments/2alcze/imo_okcoin_and_huobi_are_not_100_legit/