What is the ruling on participating in an investment company that guarantees partners fixed monthly profits, and these profits change in the event of a loss?

The aforementioned contract includes a guarantee of capital and profit, and such a guarantee is not permissible in a partnership (sharika) or a commenda (mudaraba) contract. Furthermore, the condition that a shareholder may never sell their share is considered a void condition because it contradicts the essence of the contract. Engaging in these void contracts is not permissible.