The list of listed companies needs to exclude st and pt companies. Specifically, as long as the company is st at any time on 08- 13, it will be excluded. Excel data of st and pt events come from the special processing research database of Taian database, but only the occurrence time of st and pt is recorded, and the constant time in the middle is not recorded, such as 600633 white cat st, 1 1 year in 2009. However, 10 is not displayed in the library this year. After a brief look, there are still many such situations, and it is impossible to handle them one by one by hand.