Fund products are mainly divided into: stock type, hybrid type, bond type, index type, currency type, QDII, LOF and so on. I'm not sure what fund you bought. However, according to your description, there were gains a few days ago, but there were losses in the last month, which ruled out the possibility of money funds, most likely stock funds or hybrid funds.

Some or even a large part of the investment portfolios of these two funds are invested in the stock market, so if the fund's heavy stocks (generally selected by the fund manager) plummet, the fund's net value will also drop sharply according to the corresponding proportion. So buying these funds is still risky. Just because fund managers know the market better, fund companies have a huge investment and research team, and funds invest in stocks, bonds and other markets, and the number of stocks is large, which can spread some risks and lock in some gains. However, when there are thousands of stocks in the securities market, the selected stocks can't escape the plunge. The environment is very important. Spreading risks is not to eliminate risks, and some systemic risks are unavoidable.

You can check the fund's portfolio in official website, and the daily net value can also be found. I hope I can help you.