What is the ruling on trading foreign currencies online according to the conditions mentioned?

If currency trading operations involve the client borrowing from the bank, and then the bank performs buying and selling on behalf of the client, this is impermissible. This is because the bank stipulates to the client that their buying and selling must be done through the bank, enabling it to benefit from the commission. This makes the transaction forbidden due to the prohibition of "a loan and a sale" (سلف وبيع).