How is Zakat on wealth paid for shares in fertilizer manufacturing companies?

If the company is purely industrial, manufacturing and selling fertilizers, and the shares were not purchased with the intention of trading, then there is no zakat (definition) on the value of the shares. Rather, zakat is due on the profits if they reach the nisab (definition) and a hawl (lunar year) passes over them, in which case a zakat of a quarter of a tenth (2.5%) becomes obligatory. However, if the shares were purchased with the intention of selling them when their price rises, then they are considered trade goods, and their value is assessed at market price when a hawl passes over the original capital. A zakat of a quarter of a tenth becomes obligatory on them if they reach the nisab.