The US Commodity Futures Trading Commission has sent subpoenas to four cryptocurrency exchanges asking for trading data, according to the Wall Street Journal which cited people familiar with the matter. The exchanges are Coinbase, Kraken, itBit and Bitstamp. It is from these sources that the price of Bitcoin futures as sold by CME Group is determined. CME Group is a major financial company with many different lines of business. Relevant here is its exchange in Chicago that sells financial derivatives products such as options and futures. In December of 2017 it began selling futures contracts based on Bitcoin. CME’s launch of Bitcoin futures was a pioneering step, playing a big part in bringing cryptocurrency into the mainstream consciousness. For these contracts, the price of Bitcoin is determined by taking an average of the price on the aforementioned four exchanges over an hour on the last Friday of the month.