(18)Those principles should not be taken to be exhaustive, either in terms of setting out all details of the depositary's exercise of due skill, care and diligence, or in terms of setting out all the steps that a depositary should take in relation to those principles themselves. The obligation to monitor on an ongoing basis the third party, to whom safekeeping functions have been delegated should consist of verifying that the third party correctly performs all the delegated functions and complies with the delegation contract and other legal requirements such as independence requirements and prohibition of reuse. The depositary should also review elements assessed during the selection and appointment process and compare them with the development of the market. The depositary should at all times be in a position to appropriately assess the risks related to the decision to entrust assets to the third party. The frequency of the review should be adapted so as to always remain consistent with market conditions and associated risks. For the depositary to effectively respond to a possible insolvency of the third party, it should undertake contingency planning, including the possible selection of alternative providers as may be relevant. While such measures may reduce the custody risk faced by a depositary, they do not alter reduce the obligation to return the financial instruments or pay the corresponding amount should they be lost, which depends on whether or not the requirements of Article 24 of Directive 2009/65/EC are fulfilled.