Dividends can become a source of unclaimed property because, although the issuing company pays them regularly, shareholders do not collect them.
This happens, for example, when someone unknowingly inherits shares, when an investor changes address or bank and does not notify the custodian company, or when the accounts associated with the shares remain inactive for years. The likelihood of this happening increases when the shareholding initially had a low value—which led to it being underestimated—but over time it may have appreciated and become a more significant asset.