Dr. Monzer Kahf, a prominent economist and counselor states: “First of all, we’d like to clarify that the idea of trading shares/stocks stems from the principle of owning them. Anything that is not permissible to own for a Muslim is not permissible to trade. Owning a stock or share in a company amounts to become a partner in it and becoming a partner in a company whose main line of business is not permissible is not permissible because it means you are making these Haram activities and transactions that are made the management which is in fact only your agent.
Also, we should remember that the value judgment comes only in case when the main line of business is permissible. The main line of business of conventional banks is itself haram. And there is no disagreement among Muslims on the prohibition of interest (please discard the political Fatwa that came from some countries. They have no Shari’ah foundation).“