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Mark Steenson


Mark advises on UK and EU competition law, including merger control, antitrust and subsidy control, as well as foreign investment rules.
His work includes advising with regard to multi-jurisdictional merger and foreign investment processes, cartel investigations, market investigations, subsidy control and State aid notifications, and general antitrust compliance. Mark has also worked on litigation matters in both the UK Competition Appeal Tribunal and the European Courts. Mark has also undertaken a secondment in the Phase 1 mergers division of the UK CMA.


Representative matters

A large international air carrier in proceedings before the European Courts relating to the European Commission's Airfreight cartel proceedings.

Celanese Corp in respect of global merger clearance for Nutrinova, a food ingredients joint venture with Mitsui.

Agratas Limited (a subsidiary of Tata Sons) on their plans to establish a global battery cell gigafactory in the UK with a capacity to produce 40 GW of cells annually.

Lanxess on its $1.075 billion acquisition of Emerald Kalama Chemical.

ADNOC on its joint venture with OCI N.V. to create Fertiglobe, the largest export-focused nitrogen fertiliser platform globally and the largest producer in the MENA region.

Société Générale on the global competition law aspects of the creation of a joint venture with AllianceBernstein.

Paramount Global on competition law and merger control aspects of its sale of Simon & Schuster to private equity firm KKR.

Raytheon Company on the merger and foreign investment approvals arising from its merger-of-equals with United Technologies Corporation.

A financial institution in respect of European Commission cartel proceedings into CHF LIBOR and SSA bonds.

LyondellBasell on the global and EUMR clearances for its €2.5bn acquisition of A.Schulman Inc.

Intercontinental Exchange (ICE) on the CMA’s investigation of its acquisition of London-based Trayport, a provider of software to operate trading networks for over-the-counter (OTC) energy markets. The case was the CMA’s first prohibition decision.

Jaguar Land Rover on various State aid projects, including European Commission approval for €129 regional aid in favour of its new production facility in Slovakia.

Representing the western financial investors on the financing and gas transportation arrangements for Nord Stream II.

Credit Suisse on a settlement with the European Commission in the CHF LIBOR cartel case.

Various holders of subordinated debt in challenging before the General Court the European Commission’s decision to approve State aid to Banco Espirito Santo.

Government of Croatia on State aid and public procurement compliance associated with privatization of Croatian motorway network.

Viacom on the EUMR phase I clearance for its acquisition of Channel 5.

A major international bank before the European Commission on the CHF LIBOR cartel investigations.

BMI Healthcare on the UK CMA Private Healthcare Market Investigation resulting in the first ever blocking minority in a CMA market investigation.

BMI Healthcare v. Competition Commission. Advising BMI Healthcare in its case against the CMA, the first successful judicial review quashing the CMA’s procedural approach during a live inquiry.

Tempur Sealy International on structuring its EU distribution arrangements.

Lecta Group in respect of EUMR phase I clearance on its acquisition of Italian paper merchant Polyedra.



Solicitor, England & Wales, 2012


LL.B, Law with Advanced Studies (2.1), University College London, 2009

Legal Practice Course (Distinction), BPP Law School, 2010

Postgraduate Diploma, EU Competition Law (Merit), King’s College University of London, 2015

A&O Shearman was formed on May 1, 2024 by the combination of Shearman & Sterling LLP and Allen & Overy LLP and their respective affiliates (the legacy firms). Any matters referred to above may include matters undertaken by one or more of the legacy firms rather than A&O Shearman.