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Thomas Ensign


Antitrust, competition and trade

a fantastic lawyer all round

Who’s Who Legal Competition: Future Leaders 2017

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About Thomas Ensign

Tom appears regularly before the US Department of Justice (DOJ) and the Federal Trade Commission (FTC).

He often represents clients in Hart-Scott-Rodino Act reviews of mergers and acquisitions, and in civil and criminal antitrust investigations of alleged anticompetitive conduct.

Tom also advises a wide range of clients on the full ambit of antitrust issues, including intellectual property agreements, distribution arrangements, joint ventures and other competitor collaborations, and pre-merger notification requirements in the United States and international jurisdictions.

Tom has significant experience in a variety of industries, including aerospace, aggregates, agriculture, air cargo, airlines, aquaculture, biotechnology, chemicals, computer, counterterrorism products, dairy, defense, distilled spirits, explosives, grocery, health care and hospitals, industrial gases, life sciences, medical devices, medical imaging, metals, music, natural gas, parking, pharmaceuticals, private equity, radio, satellite telecommunications, semiconductors, snack foods, software, steel, stock exchange, timber and vitamins.

Recent work

  • Advised the London Stock Exchange Group on the US and global merger control aspects of its $27bn deal to acquire Refinitiv.
  • Advising Intel, a global manufacturer of computer microprocessors and computing devices, on its $16.7bn acquisition of Altera (the largest in the company’s history).
  • Advising London Stock Exchange Group on the antitrust aspects of its acquisition of the Frank Russell Company, the owner of the Russell 2000 stock market index and operator of asset-management and stock market indexing businesses, and subsequent sale of the asset management arm, Russell Investments.
  • Advising major investment banks on multijurisdictional investigations by antitrust and financial regulators into alleged price manipulation of the benchmark, foreign exchange and credit default swap industries.
  • Advising Wincor Nixdorf, one of the leading providers of IT solutions and services to retail banks and the retail industry, on the global merger control aspects of its $1.8bn merger with US rival Diebold, creating the world’s largest ATM manufacturer.
  • Representing Emirates in air cargo international cartel investigations and related private litigation.



  • JD, University of Michigan Law School
  • BA, Vanderbilt University


  • Admitted to practice in the District of Columbia and the State of Illinois
  • Participates in the American Bar Association’s leadership:
    • currently vice chair of the ABA’s Antitrust Section’s Pricing Conduct Committee; and
    • formerly a vice chair of the ABA’s Programs and Teleseminars Committee.