Cross-checking refers to two accounts making bills in reverse, and losing money from one account to the other for many purposes, such as bribery, money laundering or seemingly earning commissions. In other words, brush the bill, but it is risky and illegal, and the exchange will strictly monitor it.

For example, Wall Street companies want to manipulate oil prices, so they buy and sell oil futures themselves, or short them, and buy call and put options at the same time, resulting in a lot of trading volume. At this time, many retail investors follow suit to buy or sell, which will lead to changes in futures prices or stock prices. The real internal cause of short-term changes in futures and stock prices is not the relationship between market supply and demand, but the transactions in the market. The share price of people who buy more goes up, and the share price of people who sell more goes down.