Bank of China is paper crude oil, which is a financial derivative linked to the international crude oil price. Banks don't go to the international commodity exchange market to buy crude oil futures directly, so they can't deliver physical crude oil, and there is no assumption of pulling back crude oil.

It is equivalent to the bank's gambling disk for investors, and investors enter the market to gamble. Banks only rely on the bid-ask spread set higher than the international oil price to make stable profits. For example, if one person buys 1 1,000 barrels and one person buys 1 1,000 barrels, and the trading points of these two people are the same, then for the bank, the two transactions are even, and the bank earns two handling fees.

The reality is that long and short transactions cannot be completely equal, so banks will hedge the extra multiple or empty orders by buying other related financial derivatives to control risks and ensure the profits of banks.