Leonidas Theodosiou focuses his practice on UK, EU, and international antitrust/competition matters and competition litigation. Leo has practiced in London and Brussels for many years, representing multinational firms in merger control proceedings, litigation in the English and EU Courts, as well as enforcement matters, including cartel, abuse of dominance, and state aid investigations. He is admitted to practice in England & Wales (Solicitor), the EU, and New York.
Prior to joining Morgan Lewis, Leo spent several years as an antitrust associate with a Magic Circle law firm, resident in Brussels. In 2018, Leo was seconded to Tata Steel—one of the world’s largest steelmakers—where he served as the organization’s in-house counsel dedicated to antitrust.
Leo’s practice is complemented by a strong academic and research record. He was a researcher at Harvard, an associate at the Committee on Capital Markets Regulation in Boston, and a doctoral researcher in competition law at Maastricht University. Leo speaks regularly at seminars and conferences and contributes frequently to leading academic and professional publications; one of his recent articles on EU state aid control was nominated as best business article at the 2020 Concurrences Antitrust Writing Awards.
Leo has received significant awards and fellowships in recognition of his research and academic achievements, including a Fulbright Fellowship by the US Department of State, and was selected to deliver the 2013 Commencement Speech at Harvard Law School.
Leo sits on the Young Lawyers & Professionals Advisory Panel of the American Bar Association’s Privacy and Information Security Committee.
Sainsbury’s Supermarkets Ltd. in relation to its claim against Visa for competition damages arising out of Visa’s UK multilateral interchange fees
A leading operator of games of chance in a number of state aid related proceedings before the General Court and the Court of Justice of the European Union (including in T-416/13, Stanleybet v. Commission; T-57/13 and T-58/13, Casino Loutraki, others v. Commission; and subsequent appellate proceedings in C-131/15)
Numerous merchants in the retail, transport and hospitality industries in relation to their claims for competition damages against Visa and Mastercard arising out of UK and EEA multilateral interchange fees imposed by Visa and Mastercard respectively
Concordia (now Advanz Pharma) in connection with challenges to CMA Search Warrants at the High Court and the Court of Appeal
Amdipharm Mercury on its defence against a Statement of Objections (SO) and a Supplementary Statement of Objections (SSO) by the UK Competition and Markets Authority (CMA) regarding an alleged pay-for-delay arrangement with respect to adrenal insufficiency drug Hydrocortisone
Concordia on its defence against the CMA’s SO and SSO and Supplementary SSO in relation to alleged unfair and excessive pricing of thyroid drug Liothyronine
Focus Pharma on its defence against the CMA’s SO in relation to an alleged market exclusion arrangement in respect of anti-nausea drug Prochlorperazine
Advanz on its defence against the CMA’s SO in relation to an alleged market sharing arrangement in respect of antibiotic Nitrofurantoin
A global manufacturing corporation on (i) its internal investigation of suspected antitrust violations; (ii) its application for immunity or leniency to antitrust enforcement agencies; and (iii) designing and implementing its organisation-wide compliance programme
A global electronics corporation in a major cartel investigation involving immunity applications in multiple jurisdictions in respect of various electronic components
Yandex on (i) the $3.725 billion combination of the ridesharing businesses of Yandex and Uber in Russia and neighbouring countries; and (ii) Sberbank’s $500 million investment in Yandex’s shopping comparison platform Yandex.Market
Tata Steel on merger control aspects of various transactions
Abbott Laboratories on its $2.9 billion acquisition of CFR Pharmaceuticals
Pfizer on global merger control aspects of various multibillion transactions
The Carlyle Group on the acquisition of a 36.8% stake from General Electric in Hong Kong listed satellite operator AsiaSat for up to $483 million
Citigroup in relation to a Phase II merger control investigation into the sale of Citigroup’s retail network in Greece to Alpha Bank
Hellenic Petroleum and the Greek Privatization Agency in relation to the European Commission’s Phase II investigation into the proposed acquisition of the Greek Ga Transmission System Operator DESFA by SOCAR
A major games of chance operator in relation to a Phase II merger control investigation into the acquisition of exclusive rights to operate horse-racing betting
A major investment management company on the acquisition of stakes in a number of Europe’s leading games of chance operators (including Casinos Austria and the Czech lottery company Sazka)
State Aid Control
A Member State’s privatization agency on state aid control aspects of a number of landmark privatizations, including (i) the extension of the concession for the operation of the country’s largest airport for €1.1 billion; and (ii) the contemplated divestment of the majority of shares in the country’s natural gas transmission incumbent
Successfully defended Citadele Bank on an in-depth investigation launched by the European Commission concerning allegedly illegal state aid
An international conglomerate on two state aid investigations into allegedly unlawful infrastructure aid
Spanish, Dutch, and Greek banks which benefitted from state aid on negotiating, implementing and/or amending their restructuring plans in line with EU state aid control rules
Harvard Law School, 2013, LL.M., Fulbright Fellow, US Department of State
University of Cambridge, Trinity Hall, 2012, LL.M.
Aristotle University of Thessaloniki, Greece, 2011, LL.B.
England and Wales (Solicitor)
Greece: Courts of Appeal
General Court and Court of Justice of the European Union
Awards and Affiliations
Member, Practice Group of the Year, Competition, Law360 (2017–2020)
Member, Law Society of England and Wales (Competition Section)
Member, International Trade and Customs Law Committee, International Bar Association