We detailed the anxiety over a more widespread crackdown on crypto-trading overnight, and since the US came back from its MLK-Day vacation, things have got worse.

It started with a repeat of South Korean finance ministry shutdown headlines.

Then Steven Maijoor, chairman of the European Securities and Markets Authority, said investors "should be prepared to lose all their money" in bitcoin, in a Bloomberg TV interview in Hong Kong. "It has an extremely volatile value, which undermines its use as a currency," he said. "It's also not broadly accepted."

That was followed by warnings from Germany's Central Bank - Joachim Wuermeling, a member of the board of Germany's Bundesbank, has suggested that any attempt to regulate cryptocurrencies would require international cooperation. Speaking at an event in Frankfurt on Jan. 15, the director told listeners: "Effective regulation of virtual currencies would therefore only be achievable through the greatest possible international cooperation, because the regulatory power of nation states is obviously limited."