Stock trading adopts bidding method, and bidding is conducted according to the rule of "price first, time first". We will see the entrusted price of buying one, buying five and selling one, selling five on the stock trading software. When investors actively sell at the price entrusted to the buyer, it will be counted as capital outflow, while when investors actively buy at the price entrusted to the seller, it will be counted as capital inflow, resulting in the difference between capital inflow and outflow.

When capital inflow is greater than capital outflow, the statistical result is net capital inflow. When the capital outflow is greater than the capital inflow, the statistical result is the net capital outflow. The transaction of capital inflow is called external disk, and the transaction of capital outflow is called internal disk.

Since active buying represents capital inflow, active selling represents capital outflow. Theoretically, when capital flows in, it means that people are actively buying, and the public is optimistic about this stock, and its share price should rise. On the contrary, the stock price should fall. But in practice, we will find that sometimes the opposite is true.

For example, if a stock is trading at a daily limit, everyone should be rushing to buy it, and there should be a large net inflow of funds, but the result is just the opposite. Let me take a stock with the latest daily limit as an example (see the figure below). The stock price went up and down, but the trading software showed that there were 23,000 lots in the external market and 73,900 lots in the internal market, with obvious net outflow of funds.

This is because A shares are subject to the price limit system, and the price limit is set after the daily limit of the stock price, that is to say, at this time, only the entrusted buying price has no entrusted selling price, so statistically speaking, there is no active buying, everyone has to entrust at the price of "buy one", and the transaction comes from active selling, so the statistical result is a net outflow of funds.

Similarly, the trading software will also show the inflow of funds when the limit is down. Look at this stock below. The stock price was opening limit, with 43,800 lots sold on the external market and 0 lots sold on the internal market. It seems that all the funds are net inflows. This is because there is no buying price after the stock price limit, and every transaction sold at the buying price will be counted as capital inflow.