What is the method for calculating zakat on subscribed shares and on traded shares that have not had zakat paid on them for years, and is zakat paid by the company or not, especially if there is a bank loan?

Zakat is obligatory on shares if they are purchased with the intention of trading, and one-quarter of one-tenth (2.5%) of their value must be paid for the past years. However, if the shares are not for trading, there is no zakat due on them intrinsically. Instead, zakat becomes obligatory on their income (dividends) if it reaches the nisab (minimum threshold) and a full year has passed over it.