1, depending on the industry: industry index funds mainly include consumption, medicine, energy, wine, banking, securities and environmental protection. In the long run, the narrow-based index funds generally needed by people's livelihood have developed well. The most typical is food, clothing, housing and transportation, medical drugs, which are inevitable expenses. There are also some sunrise industries that will focus on development in the future, which will test our investment vision. For example, we invested in the Internet ten years ago, and the future development momentum is good. Although many of them were caught by the waves, the whole industry is developing upward. In the short term, we should understand the fluctuation cycle of the industry and try to buy low and sell high.

2. Look at the manager: the tracking error and income of the narrow base are determined by the fund manager and the team behind him. The ability, investment philosophy and style of fund managers have a great influence on us.

3. Look at the price: even if you choose a narrow-based index fund, you should buy it at the right price, which requires us to look at its valuation. Low valuation funds have high security and high probability of income.