美国有线新闻 CNN 多国监管收紧 比特币持续暴跌（在线收听）

There have been some breakneck swings in the value of bitcoin. We reported on this digital form of currency last month. It was created in 2009.

People can ei?ther buy bitcoin units or mine them, use computers to solve complicated math puzzles to create bitcoin, and huge amounts of computer energy are being used to do that.

But there's a lot of uncertainty about the currency. It's volatile, highly changeable, like all cryptocurrencies. And an example of that played out in recent days when bitcoin's value took a nosedive, temporarily dropping to below $10,000 earlier this week. A single bitcoin was valued at nearly $20,000 in December.

Investors don't know exactly why the drop happened, but the Bloomberg Financial and Media Company reported early this week that Chinese officials were taking steps to limit trading in cryptocurrencies. And South Korea also took steps to regulate exchanges of digital currency.