According to a deep dive by CoinDesk, exchange data has been overstating the importance of the Japanese Yen as a trading pair. According to CoinDesk's analysis, the USD is the dominant trading currency for bitcoin ($BTC) by a wide margin. The problem is that the vast majority of yen-denominated transactions are not "spot" trades of actual bitcoin for yen. Instead, they are derivative products. The inconsistencies in how different transactions types are counted across exchanges and the different results highlight the nascent state of the cryptocurrency industry's data practices.