Jeremy Calsyn’s practice focuses on the full range of antitrust matters, including merger review, criminal and civil government investigations, and litigation, including complex class actions.

Jeremy has represented clients in their most high-profile and sophisticated matters, including mergers and acquisitions requiring regulatory approval in dozens of jurisdictions, global cartel investigations, and in litigation in federal and state courts. Most recently, he has navigated several automotive parts suppliers through U.S. Department of Justice (DOJ) and worldwide investigations into industry-wide price fixing—described by the DOJ as the largest criminal investigation it has ever undertaken.

Jeremy joined the firm in 1999 and became partner in 2008.

Notable Experiences

Merger Clearance Highlights

  • Figma in U.S. antitrust review of proposed acquisition by Adobe.

  • Deutsche Telekom and T-Mobile US in connection with T-Mobile US’s $26 billion merger with Sprint Corporation.

  • JUUL Labs in connection with a $12.8 billion investment by Altria Group in JUUL, and in subsequent litigation by the FTC.

  • ArcelorMittal in its $1.4 billion sale of ArcelorMittal USA to Cleveland-Cliffs, its previous $1.55 billion acquisition of ThyssenKrupp Steel USA through a joint venture with Nippon Steel & Sumitomo Metal Corporation, and Mittal Steel’s $33 billion acquisition of Arcelor.

  • Fresenius in its $2.4 billion combination of Fresenius Health Partners, Cricket Health, and InterWell Health to create a kidney disease-focused value-based care company.

  • Sony Pictures in its acquisition of Crunchyroll from AT&T.

  • EnCap Investments in its acquisition of EP Energy.

  • Warburg Pincus in a number of acquisitions.

  • Western Digital in its approximately $17 billion acquisition of SanDisk and in its previous $4.8 billion acquisition of Hitachi Global Storage Technology (HGST), which both required approval in the U.S., EU, China and other jurisdictions.

  • Allied Universal in its $5.3 billion contested acquisition of G4S PLC, as well as its prior acquisitions of SOS Security, U.S. Security Associates, and Universal Services’ acquisition of AlliedBarton.

  • Medtronic in its $49.9 billion acquisition of Covidien, cleared globally less than six months after announcement.

  • Vale in its $2.5 billion sale of fertilizer assets and acquisition of a minority interest in Mosaic.

  • Asahi Kasei in its $2.2 billion acquisition of the energy storage business of Polypore International.

  • Dollar Thrifty in its $2.3 billion acquisition by Hertz, as well as in the competing bids by Avis.

  • Google in its acquisition of Admeld.

  • Nortel Networks in the $4.5 billion sale of its residual patent assets through a bankruptcy auction to a consortium consisting of Apple, EMC, Ericsson, Microsoft, Research In Motion and Sony.

  • The Dow Chemical Company in its $18 billion acquisition of Rohm & Haas and its acquisition of UnionCarbide among other transactions.

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Antitrust Investigations and Litigation

  • Because of the nature of Jeremy’s assignments, many of his successful investigations have not resulted in government action and remain confidential.

  • “K” Line in winning dismissal of related price-fixing class actions brought by direct and indirect purchasers of ocean vehicle carrier services—a decision upheld by the Third Circuit and in actions before the Federal Maritime Commission, where dismissal was also affirmed;  also counsel to “K” Line in the related U.S. and global cartel investigations.

  • Aisin Seiki, Bosch, Faurecia, Omron, NSK, and Valeo in cartel investigations by the DOJ and other antitrust authorities into possible price fixing in the automotive parts industry; also defending against related civil litigation for several of the clients above, including winning dismissal of Faurecia S.A. from the civil cases and denial of plaintiffs’ class certification motion in NSK bearings MDL. In addition, Yazaki in the unanimous decision handed down by the Mississippi Supreme Court, in which it dismissed all claims brought by the Mississippi Attorney General against several manufacturers of automotive wire harnesses. 

  • Yazaki in a unanimous decision handed down by the Mississippi Supreme Court, in which it affirmed the dismissal of all claims brought by the Mississippi Attorney General against several manufacturers of automotive wire harnesses.

  • Bosch in connection with investigations and civil litigation in the U.S. regarding diesel automobiles manufactured by Volkswagen and others that used equipment supplied by Bosch allegedly to manipulate the results of vehicle emissions tests.

  • Deutsche Post’s DHL Global Forwarding business in defending against a purported class action alleging a conspiracy to fix surcharges and fees in the freight forwarding industry. Also advised DHL in related DOJ investigations, including successful amnesty applications in the U.S. and a number of other jurisdictions.

  • Asahi Glass Corporation in litigation alleging price fixing of flat glass.

  • A major financial institution in civil litigation concerning global foreign exchange (FX) trading, as well as in related regulatory matters.

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  • Former Vice Chair, ABA Antitrust Law Section, Cartel and Criminal Practice
  • Former Member, ABA Antitrust Law Section’s International Cartel Task Force


“Merger Safe Harbor for Sherman Act Violations Punishes Innocent Acquirors,” Cleary Gottlieb Alert Memorandum, March 28, 2024

Contributed to various publications on developments in antitrust laws, including the Global Competition Review, Competition Law Insight, ABA’s Annual Review of Antitrust Law Developments and the ABA’s Antitrust Law Developments. He was interviewed as part of part of the Acritas Stars™ video series on “Forging Stellar Client Relationships.”