20,30 o'clock belongs to the normal category, 50 o'clock belongs to the normal category, and it is also common above 100. In extreme cases, 300 o'clock a day is possible. If the exchange rate goes 100 in the opposite direction, it will be a loss of several thousand dollars. In contrast, interest income is not enough.

One answer is that arbitrage can be achieved by using different rules of different platforms, which is beautiful in theory but not feasible in practice. First of all, a platform without overnight interest is bound to have a huge bid-ask spread, which is determined by the cost of capital itself. Communication is objective. The wool is on the sheep, and the platform will not bear this part of the cost for customers.