The reason is that the sharp devaluation of the ruble and its fluctuation range have threatened foreign exchange traders. FXCM, the world's third largest retail foreign exchange brokerage company headquartered in new york, will stop offering roubles against the US dollar, and has started to close positions for customers. At the same time, customers are prohibited from establishing new positions and all ruble transactions are stopped. The suspension of ruble trading is to protect the interests of customers, and it is difficult to predict what serious things will happen.