Bitcoin bubble warnings issued as futures trading opens in Chicago
https://www.theguardian.com/technology/2017/dec/11/bitcoin-bubble-warnings-futures-contract-trading-chicago
First contract on a regulated exchange is seen as step towards legitimacy for the cryptocurrency but volume traded is tiny
Bitcoin has taken a step toward legitimacy with the launch of a product on a Chicago exchange that allows investors to take bets on its price in the future.