Is it permissible to sell shares of a company whose activity is forbidden to another person in order to dispose of them?

If he is able to return the shares to the company and retrieve his money, he should do so, because the sale is invalid. He should also dispose of any amount exceeding what he initially paid. If he is unable to do that, then some scholars have issued a fatwa permitting their sale in the stock market, and disposing of any resulting increase, so that he does not remain a partner in the company's unlawful activities.