To answer your first question, raising the margin of stock index futures is beneficial to brokers in the long run, because raising the margin is conducive to the normal operation of the market and avoiding many risks. The launch of the stock index is the biggest good news for brokers. The second question, which is relatively simple, is that in a country, the circulating funds used by the strata are limited, assuming that the accounts are divided between the stock market and the banks, but after the introduction of stock market futures, new profit opportunities will arise, resulting in some funds flowing from the banks to the stock market. Bank shares fell.