"Green shoe mechanism", also known as green shoe stock index futures, refers to Article 48 of the Regulations on the Administration of Stock Issuance and Underwriting issued by the China Securities Regulatory Commission in 2006: "If the total number of shares in the initial public offering exceeds 400 million shares, foreign investors and joint lead underwriters can also use it in the issuance plan to over-allocate." .

Among them, "over-matching stock index futures" is commonly known as the green shoe mechanism. Such a system can stabilize the stock trend after small-cap stocks are sold and avoid stock fluctuations and declines.

1963 the English name of Boston green shoes production company used "green shoes" in IPO for the first time, which is a comprehensive generic name for drugs with over-allotment of stock index futures.

The green shoe mechanism is mainly used for the phenomenon that the sales market is in a bad mood and the sales conclusion is not optimistic or unpredictable. Improve investors' self-confidence in participating in over-the-counter market subscription and complete the orderly promotion of over-the-counter market to secondary market. "Green shoes" can adjust the financing amount according to the market situation and balance the relationship between supply and demand in the market.