Judgment of the General Court (Fourth Chamber, Extended Composition) of 17 May 2023.#GGEW, Gruppen-Gas- und Elektrizitätswerk Bergstraße AG v European Commission.#Competition – Concentrations – German electricity market – Decision declaring the concentration to be compatible with the internal market – Action for annulment – Standing to bring proceedings – Admissibility – Obligation to state reasons – Concept of a ‘single concentration’ – Right to effective judicial protection – Right to be heard – Definition of the market – Period of analysis – Analysis of market power – Decisive influence – Manifest errors of assessment – Duty of diligence.#Case T-319/20.