The reasons why the Hang Seng Index etf is out of sync are as follows: First, the Hang Seng Index fell too deeply, which led to the low stop loss and the continuous discount of funds in the market. Secondly, because there is an error in the tracking index, the greater the trading volume, the smaller the tracking error and the better the liquidity. The smaller or even shrinking the trading volume, the greater the error of the tracking index.