What is the religious ruling on the investment portfolio in the stock market managed by the Post Authority, whose returns vary according to profit, and in which the government guarantees the deposited funds in case of loss?

For investment in a savings account to be permissible, the investment field must be Islamically lawful, the share of the capital owner and the investor in the profit must be an undivided share, and the investor must not guarantee the capital. If the guarantee is stipulated, it becomes an interest-bearing loan, and consequently, investment in the aforementioned savings account is forbidden.