  Based on the high-frequency recordings from Kraken, a cryptocurrency exchange
and professional trading platform that aims to bring Bitcoin and other
cryptocurrencies into the mainstream, the multiscale cross-correlations
involving the Bitcoin (BTC), Ethereum (ETH), Euro (EUR) and US dollar (USD) are
studied over the period between July 1, 2016 and December 31, 2018. It is shown
that the multiscaling characteristics of the exchange rate fluctuations related
to the cryptocurrency market approach those of the Forex. This, in particular,
applies to the BTC/ETH exchange rate, whose Hurst exponent by the end of 2018
started approaching the value of 0.5, which is characteristic of the mature
world markets. Furthermore, the BTC/ETH direct exchange rate has already
developed multifractality, which manifests itself via broad singularity
spectra. A particularly significant result is that the measures applied for
detecting cross-correlations between the dynamics of the BTC/ETH and EUR/USD
exchange rates do not show any noticeable relationships. This may be taken as
an indication that the cryptocurrency market has begun decoupling itself from
the Forex.
