regulated European companies offering contracts for difference (CFDs) in Bitcoin and Litecoin, as well as binary options on either.

Crypto-currency as a means of facilitating crime
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In its infancy, Bitcoin was associated with criminal activity through the online marketplace ‘Silk road’, which operated on the Dark Web. Analysing 8 months of data from this marketplace, [@christin2013traveling] found that the majority of the 24,400 items sold on the market place were controlled substances and narcotics, with 112 sellers active throughout this interval. The total revenue from public listings in this time was approximately \$10 million. Silk road was shut down by the FBI in 2013, while also seizing \$28.5 million in Bitcoin and arresting the marketplace’s operator[^14].

[@moser2013inquiry] provided the first thorough study of the potential for Bitcoin to be used as a money laundering tool. In particular, they investigated companies which provided anonymising services for a fee, by ‘mixing’ Bitcoin inputs from several participants, and generating new Bitcoin addresses to hold the outputs. They determined that some services were indeed effective for this purpose and concluded that because of this, it is unlikely that a Know-Your-Customer principle can be enforced in the Bitcoin system.

In terms of real-world use 