Is it Islamically questionable to engage in stock market speculation through an agent, where the return is high, with a stipulated percentage for the agent, provided there are no Sharia doubts and no minimum profit guarantee?

It is permissible to invest money in the stock market for profit-sharing (Mudarabah) in permissible assets, provided that Haram (forbidden) things are not purchased. It is permissible for the Mudarib (investor/manager) to receive 10% of the profit, with the remainder going to the owner of the capital. As for losses, they are borne by the capital, and the Mudarib is not liable for them unless there is transgression or negligence on their part. The condition of not terminating the Mudarabah before three months (the timing of the Mudarabah) is a point of disagreement among scholars. The safest approach is to avoid Mudarabah in international stock exchanges due to the multitude of prohibitions involved.