Is the short-term (a few minutes) buying and selling of mixed stocks permissible, given that profit comes from changes in the stock price, and that buying stocks reduces companies’ need for interest-based borrowing? And if it is assumed that usury is involved in the profit, does donating the usurious amount to charitable causes clear one’s conscience?

A mixed stock is a stock of a company whose activity is permissible, but it deals with usury by borrowing or depositing. It is not permissible to buy or sell mixed stocks because they involve both the permissible and the impermissible. The shareholder incurs sin just like those in charge of the company, as resolutions have been issued by the Islamic Fiqh Academy and the Muslim World League prohibiting dealing in mixed stocks. Therefore, buying or selling a mixed stock is forbidden, and the buyer incurs sin merely by concluding the contract. The sin increases by holding onto it and by the money entering into usury. Disposing of it immediately prevents an increase in sin, but it does not remove the sin of buying and selling and assisting in what is forbidden.