If the value of my investment in a fund decreases, do I need to top-up my investment?

No, you do not need to add more cash to your investment if the value of the shares dips below the minimum investment amount required for the Golden Visa.

Let's say you invest €500,000 into a fund and the value of those shares decreases to €480,000 in the 2nd year of holding your residence card. You do not need to add €20,000 in cash to bring the value back up to €500,000.