BBD indicator is only applicable to indexes, including Shanghai Stock Exchange Index, Shenzhen Stock Exchange Index, Shanghai and Shenzhen 3 Index, Growth Enterprise Market Index and Small and Medium-sized Board Index, which can be viewed on both K-line pages and time-sharing pages of the large-cap index. For details, please refer to the indicator in the upper right corner of level2 client. The function of BBD is to use the difference (net difference of large orders) between constituent stocks in the index as an indicator to measure the long-short strength of main funds in the market. When BBD is negative at a certain moment, it means that the sales volume of large orders at that time is large.