Jeremy Calsyn’s practice focuses on the full range of antitrust matters, including merger review across a wide range of industries, criminal and civil government investigations, litigation, and antitrust advisory work.

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. 

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

Notable Experience

Merger Clearance Highlights

  • Coursera Inc. in its merger with Udemy Inc.

  • Korean Air in its $1.3 billion acquisition of Asiana Airlines.

  • 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.

  • 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, its acquisition of Peanuts Worldwide, and numerous other transactions.

  • EnCap Investments in its acquisition of EP Energy.

  • Warburg Pincus in numerous transactions, including its $2.16 billion sale of Sundyne to Honeywell International, its acquisition of Service Express, its acquisition of Redwood Software, its $2.05 billion sale of Wencor Group to HEICO, and in its $8.9 billion sale of Summit Health-CityMD to VillageMD.

  • Sixth Street in numerous transactions, including its $7.1 billion take-private of ESR Group Ltd. as part of a consortium, and its acquisition alongside global insurance group Enstar of 100% of the shares of Accident Fund Holdings Inc. from Blue Cross Blue Shield of Michigan.

  • 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.

  • Edwards Lifesciences in numerous acquisitions.

  • Westlake Chemical Corporation in various matters, including its $1.2 billion acquisition of Hexion’s global epoxy business.

  • Pacific Woodtech Corporation in its acquisition of the engineered wood products business of Louisiana-Pacific Corporation.

  • Duravant LLC in its $230 million acquisition of Matthews Automation Solutions.

  • WPP plc in various matters, including the $1.7 billion sale of its majority stake in FGS Global.

  • Avail Infrastructure Solutions, a portfolio company of Fernweh Group, in its $975 million sale of its Electrical Products Group to nVent Electric.

  • The Dun & Bradstreet Corporation in its $6.9 billion sale to an investment group led by CC Capital.

  • ABB Ltd. on the formation of a 50/50 joint venture with the Niedax Group.

  • 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.

  • 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 as well as other transactions.

  • 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.

  • Cushman & Wakefield’s subsidiary, Pinnacle, in multi-district litigation and related investigations into alleged coordination on pricing through AI-based revenue management software.

  • Scott Sheffield, the former CEO of Pioneer Natural Resources Co, in vacating an FTC consent decree with Exxon that banned Sheffield from assuming an Exxon board seat following Exxon’s $64.5 billion acquisition of Pioneer.

  • Juul Labs in connection with a $12.8 billion investment by Altria Group, and in a successful FTC Part 3 trial challenging the investment, and related private antitrust class actions in the Northern District of California.

  • “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 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.

  • 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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SELECTED ACTIVITIES

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  • Vice Chair, Long Range & Strategic Planning Committee, ABA Antitrust Law Section
  • Former Vice Chair, ABA Antitrust Law Section, Cartel and Criminal Practice
  • Former Member, ABA Antitrust Law Section’s International Cartel Task Force

Publications

The Old HSR Form is Back (For Now),” Cleary Gottlieb Alert Memorandum, March 20, 2026

U.S. District Court Vacates FTC’s 2024 HSR Filing Rule,” Cleary Gottlieb Alert Memorandum, February 13, 2026 

California Enacts Uniform Antitrust Premerger Notification Act,” Cleary Gottlieb Alert Memorandum, February 13, 2026

2026 HSR Thresholds Announced,” Cleary Gottlieb Alert Memorandum, January 15, 2026

Cooperation, Not a Cartel – Why Lender Co-op Agreements Should Generally Withstand Antitrust Scrutiny,” Cleary Gottlieb Alert Memorandum, December 18, 2025

FTC and DOJ Release Contingency Plans Ahead of Potential Government Shutdown,” Cleary Gottlieb Alert Memorandum, September 29, 2025

DOJ Antitrust Division Warns About “Product-Fixing” Risk,” Cleary Gottlieb Alert Memorandum, July 2, 2025 

Colorado Enacts Uniform Antitrust Pre-Merger Notification Act as California and New York Progress Their Own Bills,” Cleary Gottlieb Alert Memorandum, June 12, 2025 

Washington State Enacts Uniform Antitrust Premerger Notification Act,” Cleary Gottlieb Alert Memorandum, May 1, 2025 

Antitrust Agencies Issue Revised Labor Guidance in Waning Days of Biden Administration,” Cleary Gottlieb Alert Memorandum, January 22, 2025 

New HSR Thresholds Announced as February 10 Go Live Date for New HSR Rules Looms: Will Congress or the Courts Intervene and What You Can Do Now,” Cleary Gottlieb Alert Memorandum, January 14, 2025 

Revised DOJ Antitrust Compliance Guidance Provide a Tool for Evaluating Corporate Compliance Programs,” ABA Antitrust Law Section, November 20, 2024 

DOJ Antitrust Creates Guidance for Evaluating Antitrust Compliance Programs,” Cleary Gottlieb Alert Memorandum, November 20, 2024

UPDATE: Changes to U.S. Premerger (HSR) Rules to Take Effect on February 10, 2025,” Cleary Gottlieb Alert Memorandum, November 11, 2024

Final Changes to Premerger (HSR) Process in the United States Adopted by Enforcement Agencies,” Cleary Gottlieb Alert Memorandum, October 17, 2024 

US Antitrust Regulators Threaten Ephemeral Messaging Users and Their Counsel With Obstruction Charges,” Cleary Gottlieb Alert Memorandum, June 7, 2024 

“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.”

Events