2 refers to the weighted index stocks accounting for about 20% of the stock market, and 8 refers to other non-index stocks accounting for about 80% of the stock market. The trend is that weighted index stocks are rising and other non-index stocks are falling. The "28" trend originates from the "28" law, which is also called Pareto Law and Bale Law.

The law of 28 was discovered by the Italian economist Pareto. Pareto believes that in any group of things, the most important thing only accounts for a small part, about 20%. Although the remaining 80% is the majority, it is secondary. Investors applied the 28-28 law to the stock market and got the 28-28 trend.

If the market index is not driven by the rise of most stocks, but by the continuous rise of a few weighted index stocks, it is called the 28 th phenomenon. Under the leadership of blue-chip stocks with heavy weights, the stock index keeps hitting new highs, and the flow of funds tends to be concentrated, gradually evolving into the "28" phenomenon.

Compared with the trend of 28, it is the trend of 82, indicating that other non-index stocks are rising, and the weight index stocks are falling. With the continuous introduction of warrants, stock index futures, margin financing and securities lending and other trading means and derivatives, the "28" trend will become more prominent.

28 phenomenon is a common phenomenon in developed foreign stock markets. With the continuous improvement of China's economic strength, the "February 28th" phenomenon will become a common phenomenon in China stock market.