The answer is surprisingly easily, whether it is simple explanations such as hidden assets, unknown trusts, assets located in foreign jurisdictions, assets subject to intestacy or administrative mistakes, errors in processing systems or data, to more complex causes such as insolvency events, incorrect corporate dissolution, assets subject to complex or lengthy disputes, corporate actions, or assets incorrectly appropriated following mergers and acquisitions. Often the amounts involved can be insignificant on their own but over many years can become substantial. Those entities which operate from multiple locations and jurisdictions, have many subsidiaries and have been in existence for long periods of time are more susceptible to the risk of lost assets, as are individuals who move frequently between locations.