1. The Member States or competent authorities shall require a payment institution which provides any of the payment services listed in the Annex and, at the same time, is engaged in other business activities referred to in Article 16(1)(c) to safeguard funds which have been received from the payment service users or through another payment service provider for the execution of payment transactions, as follows:
either:
(a) they shall not be commingled at any time with the funds of any natural or legal person other than payment service users on whose behalf the funds are held and, where they are still held by the payment institution and not yet delivered to the payee or transferred to another payment service provider by the end of the business day following the day when the funds have been received, they shall be deposited in a separate account in a credit institution or invested in secure, liquid low-risk assets as defined by the competent authorities of the home Member State; and