OKCoin recently announced the suspension of bitcoin withdrawals from its exchange in order to improve AML practices, and other Chinese exchanges soon followed with similar announcements. Portfolio company Tradeblock's XBX bitcoin index continued to provide a reliable reference rate for bitcoin throughout this irregular activity.
Although the XBX algorithm functioned as intended and mitigated the need for manual intervention, the sustained breach of a core principle for inclusion in the index warranted an exceptional review process. As such, OKCoin will be removed as a constituent of the XBX index over the next 24 hours. During the next XBX quarterly review in April, OKCoin’s eligibility will be reevaluated along with that of all relevant exchanges that could potentially qualify for inclusion under TradeBlock’s guidelines.
https://tradeblock.com/blog/xbx-index-update-removing-okcoin