Is it considered usury to trade in the stock market, which involves buying shares with a partial amount of capital, while paying a fixed commission to the company without additional interest? And does the ruling on this transaction differ from the company's request to buy shares with an amount exceeding the capital, provided that the amount is settled later in cash or by selling the shares, knowing that the investor's shares are the guarantee?

It is impermissible to borrow from a brokerage firm for investing in stocks, because it is a loan that draws a benefit, and that is usury (riba). The benefit here is the commissions the company earns from buying and selling stocks. The ruling does not change whether the loan is repaid from profits or from selling the shares. However, if the client invests with their own money without borrowing, it is permissible, provided that the stocks are Sharia-compliant (pure), and that the Sharia guidelines for buying gold, silver, and currencies are observed, such as the condition of immediate mutual possession (taqabud).