Are shares subject to Zakat, and what are their Nisab and Zakat rates if their owner does not wish to sell them now?

If the shares are fixed assets intended for benefiting from their annual yield, then zakat is not obligatory on the principal of the shares, but rather on their yield if it reaches the nisab and a hawl (lunar year) has passed over it. However, if the shares include trade goods, then zakat is paid according to the proportion of those goods. If they were purchased with the intention of trading, then they are subject to zakat as trade goods if a hawl has passed over their original price and their value reaches the nisab. One-quarter of one-tenth (2.5%) of their value is to be given, and the nisab is the equivalent of 85 grams of gold or 595 grams of silver.