Is buying investment certificates from an investment bank, knowing that the profit margin after 10 years is 300%, considered usury (riba) and forbidden? And what is the way to invest this money if trade is not feasible?

Investment certificates issued by usurious banks and institutions are forbidden, and one must repent from them and withdraw the capital paid to the bank. As for the profits, they must be disposed of by spending them on the poor and charitable causes. Ignorance of investment methods does not permit engaging in usury. Among the permissible investment methods is Mudarabah (profit-sharing) with money, according to its legitimate conditions.