Stock index futures is a high-risk investment product, with a large amount of funds and strong volatility, which is easy to cause psychological pressure on traders. In trading, if the position loss is too large, investors need to take timely measures, such as adding margin, lightening positions or stopping losses. If effective measures are not taken, stock index futures may be forced to close their positions. So, when will stock index futures be closed?

First of all, when the holder's margin is insufficient, the exchange will force the liquidation. The exchange of stock index futures adopts the principle of daily margin, that is, if the loss of the day exceeds the margin level of the contract held, additional margin is needed. If the holder can't add margin, then the stock index futures will be forced to close.

Secondly, when the contract expires, stock index futures will also be forced to close their positions. After the contract expires, if the holder does not close the position in time, the stock index futures will be closed by the system. In this case, the holder can neither make a profit nor lose all the deposits.

Finally, when the market fluctuates violently, stock index futures may also be forced to close their positions. In this case, when the market fluctuates greatly, the exchange may change the margin standard, resulting in insufficient margin for the holders, thus triggering the system to force liquidation.

To sum up, stock index futures will be forced to close their positions when the margin is insufficient, the contract expires and the market fluctuates violently. Therefore, investors need to master investment risks and take effective measures to avoid risks when trading stock index futures. Only in this way can we get a better return on investment in stock index futures trading.