Even if you buy through a bank and the fund carries the bank's name, there is no guarantee. You can lose money.
Some types carry more risk than others.
Understand that a higher rate of return typically involves a higher risk of loss. Past performance is not a reliable indicator of future performance. Beware of dazzling performance claims. ALL mutual funds have costs that lower your investment returns. Others are sold mainly through brokers, banks, financial planners, or insurance agents.