Is it sufficient to give 20% as charity to purify money earned from selling shares of Al-Salam International Company, given ignorance of the nature of the company's activities and revenues?

A ruling cannot be made on a specific company without knowing its activities. One must adhere to Sharia guidelines when purchasing shares, and it is impermissible to invest in a company unless its activities and resources are known. If the company's activity is permissible (halal), then there is no need to purify the profits. However, if it is forbidden (haram) or mixed with something forbidden, then the entire forbidden portion must be disposed of. Estimation is resorted to in cases where the amount of forbidden money is unknown, so that the person disposes of what he predominantly believes will clear his liability.