Case C-50/19 P: Judgment of the Court (Grand Chamber) of 6 October 2021 — Sigma Alimentos Exterior SL v European Commission (Appeal — State aid — Article 107(1) TFEU — Tax system — Corporate tax provisions allowing undertakings which are tax resident in Spain to amortise the goodwill resulting from the acquisition of shareholdings in companies which are tax resident outside that Member State — Concept of ‘State aid’ — Condition relating to selectivity — Reference system — Derogation — Difference in treatment — Justification for the difference in treatment)