米国：SECが，Bitcoinのような仮想通貨への投資は極めて危険であるとの警告

下記の記事が出ている。

　Bitcoin buyer beware: US SEC warns 'extreme caution' over cryptocurrency investments
　Guardian: 12 December, 2017
　https://www.theguardian.com/technology/2017/dec/12/bitcoin-buyer-beware-us-sec-warns-extreme-caution-over-cryptocurrency-investments

　The SEC Chair's Cryptocurrency Warning: 5 Things to Know
　Fortune: December 12, 2017
　http://fortune.com/2017/12/12/cryptocurrency-blockchain-ico-sec/