(21)When delegating safekeeping functions, the depositary should ensure that the requirements of Article 22a(3)(c) of Directive 2009/65/EC are fulfilled and that the assets of the UCITS clients of the depositary are properly segregated. This obligation should particularly ensure that assets of the UCITS are not lost due to insolvency of the third party to whom safekeeping functions are delegated and that assets of UCITS are not reused by the third party on its own account. Furthermore, the depositary should be allowed to prohibit temporary deficits in client assets, use buffers or put in place arrangements prohibiting the use of a debit balance for one client to offset a credit balance for another. While such measures may reduce the custody risk faced by a depositary when delegating safekeeping functions, they do not alter the obligation to return the financial instruments or pay the corresponding amount where these are lost, which depends on whether or not the requirements of Directive 2009/65/EC are fulfilled.