What is the ruling on trading in shares where the workers guarantee no loss and profits reach 30% monthly, along with their claim that these are halal shares for local currencies and companies?

It is permissible to engage in international stock markets if the Sharia controls are adhered to. However, most of them involve usurious contracts, speculative contracts, and margin buying, which are not permissible according to Sharia. Therefore, it is not permissible to place money in these offices unless their adherence to Sharia controls is known, and their transactions must be thoroughly investigated. The condition of guaranteeing the capital is void, because this is not valid in Mudarabah (profit-sharing partnership), as losses are incurred from the capital.