Futures are settled at the daily closing. Whether you hold a position or not, the settlement price is the weighted average price of the trading volume of the day. Your deposit consists of two parts: performance bond and effective bond. When you don't have a position, the funds in your account are available bonds. When you have a position, the deposit required for holding the position is the performance bond. When the available bonds in your account are negative, the futures company will inform you to increase the margin or reduce the position to ensure the capital risk.