It is possible to judge arbitrage according to premium rate. Because the futures price is a future price, that is, ahead of the spot price, if there is a premium, it may lead to some arbitrage of funds. Theoretically, when the futures premium rises, investors will buy the spot and sell the futures. Or buy short-term contracts and sell long-term contracts. On the other hand, this constant arbitrage behavior also makes the spot prices finally tend to be consistent. However, the application of futures premium in practice is by no means so simple, and its judgment is also influenced by many factors. Especially for stock index futures, its premium and discount are determined by interest rate level, dividends, securities lending rate, market sentiment and other factors. Whether the futures index is higher or lower than the current index does not mean to look up or down the future stock market. You still need to learn and use it in actual combat.