For individual stocks, the major influence is large-cap stocks, because large-cap stocks have a greater weight in the index. Then, controlling these heavyweights is equivalent to controlling the market index, and stock index futures are traded with margin, so you can get more benefits with less money. Therefore, generally speaking, institutions can buy stock index futures while suppressing the index through heavyweights, thus obtaining greater returns than the stock market. Of course, we can also raise the index by pulling up the heavyweights, and at the same time buy out the stock index futures to get the same benefits as the futures market and the stock market.