Judgment of the Court (Second Chamber) of 19 December 2019.#Arriva Italia Srl and Others v Ministero delle Infrastrutture e dei Trasporti.#Reference for a preliminary ruling — State aid — Notion — Public railway undertaking in difficulties — Aid measures — Allocation of financial aid — Aim — Continued operation of the public railway undertaking — Allocation to and shareholding in the capital of that public undertaking — Transfer to the capital of another public undertaking — Private investor test — Prior notification obligation for new aid.#Case C-385/18.