Stéphane Dionnet has nearly 20 years of experience advising on European Union and international competition law. He regularly advises clients in relation to some of the world’s most complex and significant merger control reviews. 


Mr. Dionnet also has assisted clients in numerous cartel investigations, in particular with respect to immunity/leniency applications before the European Commission and other international competition agencies, as well as corporate investigations relating to cartels. He has worked with clients from a diverse range of industries including consumer products, energy, entertainment, financial services, pharmaceuticals, retail and telecommunications.

Mr. Dionnet has repeatedly been included in Who’s Who Legal: Competition - Future Leaders and named as a Next Generation Lawyer in Legal 500 Competition: EU and Global. Mr. Dionnet also has was included in Expert Guides: Rising Stars’ 2019 edition.

Prior to joining Skadden, Mr. Dionnet worked for three years within the “Merger Network” of the European Commission’s Directorate-General for Competition. He was case-handler in high-profile transactions in various industries including pharmaceuticals (Sanofi-Synthélabo/Aventis), entertainment (Sony/BMG), medical devices (Johnson & Johnson/Guidant), software (Microsoft/Time Warner/ContentGuard JV) and freight (CIMC/Burg). He also participated in “dawn raids” conducted by the European Commission in the context of cartel cases.

Mr. Dionnet’s experience includes advising, among others:

  • ABB Ltd in connection with its:
    • US$7.8 billion sale of a 80.1% stake in its Power Grids division to Hitachi, Ltd.; and
    • US$2.6 billion acquisition of General Electric Industrial Solutions;
  • Becton, Dickinson and Company on its US$12.2 billion acquisition of CareFusion Corporation;
  • DSV A/S, a Danish logistic group, in connection with:
    • its US$4.6 billion acquisition of The Panalpina Group; and
    • its US$1.34 billion acquisition of UTi Worldwide Inc. through a cash merger;
  • EMC Corporation on its proposed US$67 billion acquisition by Denali Holding Inc., the parent company of Dell Inc.;
  • International Paper Company in its acquisition of two packaging businesses in northwestern France and Portugal from DS Smith Plc;
  • LANXESS AG in its US$2.5 billion acquisition of Chemtura Corporation;
  • Qlik in its US$3 billion acquisition by Thoma Bravo, LLC, following Qlik’s review of strategic alternatives; and
  • Wendel SE and its portfolio company AlliedBarton Security Services LLC in AlliedBarton’s merger with WarburgPincus-backed Universal Services of America, Inc.

Mr. Dionnet also has successfully assisted companies in obtaining conditional immunity with the European Commission and other competition law agencies in and outside the EU. Recent representations include the immunity and leniency applicants in the EU power cables and car battery recycling cartel investigations, respectively.



  • LL.M., (European Law) College of Europe Bruges, 2001
  • LL.M., (Contract and Commercial Law) University of Helsinki, 2000
  • D.E.S.S., (European Business Law) University of Paris V, Descartes, 1999
  • Maitrise, (European Law) University of Paris I, Sorbonne, 1998
  • License, Lapland University, Rovaniemi, Finland, 1997
  • DEUG, University of Orléans, 1996


  • Brussels


  • French
  • English

Stephane Dionnet