What is the ruling on zakat for pure shares if a Ḥawl (full lunar year) has not passed on them, and do the companies invested in pay zakat on behalf of the investor?

Zakat is obligatory on shares prepared for trade if a complete year (hawl) has passed over them and they have reached the minimum taxable amount (nisab), either on their own or when combined with other assets. It is a condition that each partner pays zakat on his share of the capital and profits. It is permissible to pay zakat in advance before the hawl is due, and there is no harm in appointing trusted companies to disburse it.