And here's something for cryptocurrency traders to worry about. The People's Bank of China ordered financial institutions on Friday to stop providing banking or funding to any cryptocurrency-related activities. ZHENG CHUNYING has the story.

A further step in the crackdown on cryptocurrencies. The People's Bank of China released a circular on Wednesday, banning all services for cryptocurrency transactions. The document said that Banks should enhance their daily transaction monitoring, and orders the timely shut down of payment channels once any suspected trading of cryptocurrencies is discovered. At one point on Friday, the prices of some of the main digital currencies tumbled over 7 percent. The plan follows China's crackdown on cryptocurrency trading last year, which saw Beijing shut down bitcoin exchanges and ban all initial coin offerings. The government deems cyber money too risky to allow its continued trade.

ZHAO KUNPING, CHIEF ANALYST BANK OF COMMUNICATIONS "Although our financial markets have developed a lot, the investment options are still limited. So there was a lot of bitcoin investment in China. The regulator has always focused on containing risks, and of course, there are a lot of risks in the financial sector - high leverage, shadow banking, local government debt. Bitcoins raised the possibility of triggering even more risks, so it was necessary to control it.

And China is not the only country that strives to control the risk. Many other countries and institutions are busy introducing new rules to rein in the market. The European Central Bank has called for bitcoin to be regulated and taxed, labelling the cryptocurrency a tool for money laundering. The South Korean government also said it will regulate speculation in cryptocurrency trading within the country. There's fierce debate over whether the future of bitcoin is a dangerous speculative bubble. But one thing is for sure, the digital currency's volatility remains an ever-present reminder that no-one actually knows the true value of the currency. ZHENG CHUNYING CGTN.