What is the ruling on fees paid from the capital of a person who directed it to investment companies that offer guaranteed returns, knowing that guaranteeing returns in investment is impermissible?

Brokerage fees resulting from facilitating a permissible matter are lawful. However, if they result from facilitating a prohibited matter, they are unlawful, as this constitutes cooperation in sin. Based on this, it is not permissible to facilitate companies that offer guaranteed returns for the first two years, because such arrangements are either usury (riba) or فاسدة (invalid/corrupt) partnerships. Consequently, the brokerage fee for them is unlawful. It is obligatory to investigate the company's activities and investment methods. If they are lawful, then there is no objection to taking a facilitation fee, whether it is a fixed amount or a percentage.