Is it permissible to open accounts with an online company where the balance is the weight of precious metals (gold, silver, platinum, palladium), knowing that the company takes an annual commission on the quantity of metal, and that buying, selling, withdrawing the balance, and converting it into currencies are done through other brokerage firms?

If the aforementioned company does not engage in usurious activities, but rather takes an annual commission as a fee or administrative expenses, then there is no harm in opening an account with it and depositing money for safekeeping. The fact that the safekeeping fee is a percentage proportional to the quantity of the metal does not invalidate its permissibility, because the balance is known, and a percentage of a known amount will also be known.

If the company resorts to another brokerage firm to buy or sell the metal and convert the balance to the chosen currency, while taking a commission, there is no harm in that, unless there is another reason for prohibition.

It should be noted that this type of company may not protect its clients from falling into unlawful acts or fraud, and a person is obliged to safeguard their wealth.