VOL-TDX index is used to predict the whole-day trading volume of the last K-line of the day, which is convenient to compare with the previous trading volume.

Shrinkage is the reduction of trading volume, while heavy volume is the amplification of trading volume. When the stock price rises, it is normal to enlarge the trading volume; It is a good thing that stocks have fallen and trading volume has shrunk. Stocks rise quickly, especially when they break through the pressure level. The volume of transactions should be effectively enlarged, otherwise the breakthrough will be invalid and they will face a callback. If the stock falls, if it is not shrinking, it is heavy, that is, institutional shipments, and it should leave in time.