https://motherboard.vice.com/en_us/article/59db3a/three-of-chinas-biggest-bitcoin-exchanges-are-shutting-down

Two of China's largest exchanges for buying and selling Bitcoin, OKCoin and Huobi, announced on Friday that they will stop trading Bitcoin for Chinese yuan effective immediately. The reason, the exchanges stated, is to comply with Chinese government directives issued on Thursday.

While the suddenness of the Bitcoin trading ban was surprising, it reflects a larger trend in China toward regulating crypto markets. Earlier this month, China's central bank outlawed Initial Coin Offerings—a method of raising capital for blockchain-based companies—in a telltale sign that the country was moving to tighten regulations on cryptocurrencies. China is a major hub for Bitcoin mining, a resource-intensive process that confirms transactions and updates Bitcoin's public ledger, the blockchain.