This is an arbitrage transaction. You can't place an order casually, or you will have to pay a handling fee, which generally won't explode, but arbitrage is often operated by Man Cang. If the market continues to reverse, there may be a situation where the available funds are negative and additional margin is needed, otherwise it will be strong.

Such as soybean meal and beans, one is short and the other is short. Related varieties have the same trend, but there will be times when they rise more and fall less.