European Union – Employment. Article 1(1) of Council Directive (EC) 2001/23 should be interpreted as meaning that the transfer, to a second undertaking, of financial instruments and other assets of the clients of a first undertaking, following the cessation of the first undertaking's activity, under a contract the conclusion of which was required by national legislation, even though the first undertaking's clients remained free not to entrust the management of their stock market securities to the second undertaking, could constitute a transfer of an undertaking or of part of an undertaking if it was established that there had been a transfer of clients, that being a matter for the referring court to determine. The Court of Justice of the European Union so held in proceedings concerning the lawfulness of the termination of the applicant employee's employment contract.