The so-called black market is a market transaction that is no longer under the jurisdiction of the government, so it is natural that the exchange rate is different from the official.

The black market purchase price is higher than the legal channel, which is actually a premium, including risk factors, liquidity factors and costs.

If the black market wants to avoid being caught by the police, it needs to bear greater risks, so it has higher requirements for prices, which is a risk premium.

Settlement and sale of foreign exchange through normal channels requires a lot of supporting documents, and as long as there is money on the black market, it is a liquidity premium.

In addition, in order to attract more foreign exchange inflows, the black market will offer a higher purchase price than the legal channels, so the selling price will be higher than the bank's quotation.

Generally speaking, the worse the liquidity of a currency, the stricter the control, and the greater the deviation between the black market price and the positive price.