What is the ruling on paying a sum of money to an investment company that operates in the global stock market by trading currencies and oil, on the condition that the company enters into each transaction with ten percent of the capital and completes the remainder, and takes 35 dollars for its services, without being related to profit or loss?

This transaction is classified as an agency for a fee, where an individual appoints an investment company to conduct buying and selling operations in currencies and oil in exchange for a known fee ($35 for each transaction). The problem lies in the amount the company pays: if it lends the principal without an increase beyond the agency fee, then there is no objection. However, if it takes anything extra or if the fee varies according to the amount borrowed, then the transaction is impermissible because it is a usurious loan.