a fund's portfolio will change, but it's not like what you described: if the stock market is not good, it's better to invest less in stocks and more in currencies and bonds to avoid risks.
during the issuance period, each fund has determined its investment scope. For example, the stock position of stock funds cannot be less than how much.
and every quarter, the fund is constantly changing positions, mainly to adjust the stock varieties, not necessarily to buy currencies and bonds, but to buy currencies and bonds according to the behavior of market changes.