Closing profit and loss = historical closing profit and loss+current closing profit and loss = ∑ [(selling closing price-settlement price of the previous trading day) × selling closing amount]+∑ [(settlement price of the previous trading day-buying closing price )× buying closing amount] closing profit and loss = ∑ [(selling closing price of the current day-buying opening price of the current trading day )× selling closing amount] +∑ [Mark-to-market position profit and loss = historical position profit and loss+opening profit and loss of the day = (settlement price of the day-settlement price of the previous trading day) × opening profit and loss of the day = ∑ [(settlement price of the day-settlement price of the day )× opening price of the sale]+∑ [(settlement price of the day-opening price of the purchase )× opening price of the purchase] Today's profit and loss can be integrated into a general formula: today's profit and loss =