Is it obligatory to take out a loan to pay the zakat on invested shares in an Islamic bank, or is it permissible to wait until receiving cash dividends or additional shares, especially if it is difficult to determine the profits and the bank delays in notifying them?

Zakat is obligatory on deposited money and its profits if it reaches the نصاب (minimum threshold) and a hawl (lunar year) has passed on it. It is not permissible to delay its disbursement when one is able to do so. If the giver of zakat is unable to disburse it due to an excuse, there is no sin upon them, and they must strive to disburse it as soon as possible. It is not obligatory to borrow money to disburse zakat, but if you do so, it is good as long as you are able to repay the debt. If the questioner is unaware of the amount of profit from her deposit, she should ask or estimate it based on what is most likely. If it becomes clear that what she disbursed was less, she should complete it. If it was more, she should deduct the difference from the zakat of the coming year, unless she willingly gives it to the poor.