(28)It should first be determined whether the event which led to the loss was external. The depositary's liability should not be affected by the delegation of safekeeping functions and therefore an event should be deemed external if it does not occur as a result of any act or omission of the depositary or the third party to whom the safekeeping of financial instruments held in custody has been delegated. Then, it should be assessed whether the event is beyond the depositary's control, by verifying that there was nothing a prudent depositary could reasonably have done to prevent the occurrence of the event. Under these steps both natural events and acts of a public authority may be considered as external events beyond reasonable control. In contrast, a loss caused by failure to apply the segregation requirements laid down in Article 21(11)(d)(iii) of Directive 2009/65/EC or the loss of assets because of disruption in the third party's activity in relation to its insolvency cannot be seen as being external events beyond reasonable control.