Dude, have you seen Master of Short-term Trading? In QT, a software that looks at pictures of American stocks, there is this Tick index, which mainly refers to the index of a typical stock set of a certain stock. Its meaning is the same as the market index, indicating the overall situation of a certain type of stock. This thing is designated, and it is useless now. Don't dwell on it. The core idea of this book is very important. Even a spy can do it, or DJ30 is not bad.