What is the ruling on Zakat for shares bought with the intention of benefiting from their dividends and selling them when needed? Are these considered trade shares or investment shares? And what should I do if the Zakat fund delays in determining the Zakat percentage for shares? Should I pay Zakat at the previous year's percentage and then pay the difference?

You have done well by limiting yourself to purchasing shares of permissible companies. As for the zakat on shares that are not for trading, it is not obligatory on the principal of the share itself, but rather on its yield, at a rate of one-quarter of one-tenth (2.5%) after a year has passed from the day it was received, provided that the company's shares are fixed assets. However, if they are commercial goods, then zakat is due on both the capital and the profit. If the company undertakes to pay the zakat, it stands in the place of the owners. The intention to sell shares out of need does not change the ruling of zakat; it changes only if the shares were initially bought for trading. If zakat becomes obligatory upon you, it becomes due at the completion of the year and is calculated based on the market value of the shares.