Trading In Banking Stock
The issue here is not of earning interest through trading of stock, rather it is to invest/trade in a stock of a company whose primary revenue generating activity is interest based . Share price is backed by the activity of the company, therefore one is not only involved in keeping afloat the primary activity of the bank, which is riba based primarily hence prohibited, but is also involved in reaping benefits from the fluctuations in the share price of the bank.