What role did stock index futures play in the financial turmoil? This is a topic that the market has been paying more attention to. The "87 stock market disaster" in the United States initially identified stock index futures as the "culprit". However, after research, it is found that stock index futures are not the real behind-the-scenes pusher of the stock market crash. On the contrary, stock index futures have played a positive role, just like an indispensable "rescue" force. When disaster strikes, investors often can't accurately predict the extent of losses, and then sell wildly in financial markets to avoid risks. For example, the trauma caused by the earthquake in Japan will be enormous, but more accurate reports of casualties and property losses will not be available until 100 hours later, while Japan's Nikkei index fell by 15% within three trading days after the earthquake. Similar to the financial crisis in 2008, the trading volume of Nikkei futures index increased significantly after the earthquake, which effectively slowed down the risk of stock market crash from four aspects.

Hedging mechanism mitigates market impact.

Reduce the selling pressure and market impact in the spot market through hedging mechanism. After the earthquake, some institutional investors, such as large funds and insurance funds, hedged by short selling Nikkei stock index contracts, effectively avoiding the risk of falling market value of portfolios and greatly reducing the impact effect and "killing more" caused by a large number of stocks. Therefore, it is no accident that the volume of Nikkei stock index contracts has increased significantly, which has played a more important and positive role in stabilizing the market.

Arbitrage mechanism stabilizes the fluctuation range of stock spot market.

The stock index futures market is mainly composed of diversified investors such as arbitrageurs, hedgers and speculators, as well as complex trading mechanisms such as short selling, arbitrage and hedging, which are conducive to restraining excessive price deviation and realizing the function of price discovery. Among them, the arbitrage mechanism can effectively restrain the excessive deviation of stock index contract from stock index, and make the stock index futures price and stock index in a reasonable fluctuation range.

The price discovery mechanism is conducive to stabilizing market sentiment.

Modern finance believes that financial markets can take advantage of people's panic to arbitrage. The contract price of stock index is a rational expectation of the future stock price level. Because there is no urgent selling pressure from the spot market, stock index futures, especially forward contracts, can evolve the future stock price trend more calmly and rationally, and form the forward contract price through the price discovery mechanism, which can calm the market panic to some extent.

Abundant liquidity reduces market panic.

When the market is shrouded in panic, the lack of liquidity becomes an important reason for the market panic, and stock index futures can just provide some liquidity for the spot market of stocks, giving investors the opportunity to hedge or withdraw from the market, thus alleviating the market panic. This is the internal reason why stock index futures have invested a huge amount of money to stabilize the market in previous major crises.

The above four aspects briefly describe the positive role of stock index futures in financial market turmoil. Of course, as an extension of the stock spot market, stock index futures is only a tool for stock market risk management, and it is impossible to change the fundamental situation and the basic trend of stock market operation, but it is only helpful to slow down the stock market crash. Domestic stock index futures have been listed for nearly a year, both based on historical data and intuitive trend analysis reflect the basic fact that the fluctuation range of stock spot index has decreased obviously after the listing of stock index futures. During this period, the stock index futures market developed steadily and played an important and positive role in stabilizing the domestic A-share market.