Is buying shares in American companies specializing in computers and pharmaceutical manufacturing through a broker in an interest-based bank permissible or forbidden, and what should be done if it is forbidden?

Your taking the step to buy shares with usury is impermissible, and you must repent from it. As for your investment in the aforementioned companies with this money, it is permissible under two conditions. It is not permissible to continue opening an account in a bank that deals with usury, and you must repent and seek forgiveness for what has passed.