Department profile
Simpson Thacher & Bartlett LLP

Antitrust

USA Guide 2026 : District of Columbia

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Simpson Thacher & Bartlett LLP

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About

Provided by Simpson Thacher & Bartlett LLP

Simpson Thacher offers a premier Antitrust and Trade Regulation Practice providing unparalleled advice on clients’ global competition needs. The Firm advises on complex, bet‑the‑company matters across major industries, with a team including former FTC and DOJ officials. Plaintiffs and defendants turn to us for high‑profile antitrust litigation, where our successes span trials, dismissals and appeals shaping antitrust law. Clients turn to us for our record in achieving regulatory clearance for the largest and most complicated M&As in history. The Firm has recently achieved landmark victories in multiple high-profile litigated merger cases versus the DOJ and FTC, including UnitedHealth Group/Change Healthcare; Tempur Sealy/Mattress Firm; and HCA/Louisiana Childrens Medical Center. We also advise on Second Request investigations, maintaining real‑time engagement with agencies on highly strategic matters. The Firm won “Merger Control Matter of the Year – Americas” at the 2026 Global Competition Review Awards for representing Amedisys in defeating the DOJ’s challenge to its UnitedHealth merger, and “Litigation of the Year – Cartel Defense” at the 2025 Global Competition Review Awards for securing dismissal affirmance for JPMorgan in ICE LIBOR litigation. The Firm was recognized as a 2026 "Global Elite" Firm by Global Competition Review in its annual GCR 100 report, and is consistently recognized as a leading antitrust practice by The Legal 500 and Benchmark Litigation.

Chambers Review

Provided by Chambers

Antitrust - District of Columbia

Band 3

What the Team is Known For
Simpson Thacher & Bartlett LLP has a consummate team of antitrust practitioners who adeptly handle high-value merger clearance matters and government investigations conducted by the FTC, DOJ and European regulatory authorities. Also represents plaintiffs and defendants in high-profile litigations involving claims such as monopolization and price fixing, among others. Experience representing multinational corporations in international and national cartel investigations and subsequent litigation.
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Work Highlights

Provided by Chambers

  • Simpson Thacher & Bartlett LLP represented Mattress Firm Group in its successful $5 billion acquisition by Tempur Sealy.

Strengths

Provided by Chambers

  • Simpson has excellent knowledge of antitrust laws. The team provides in-depth and practical advice on many antitrust issues.

    Antitrust respondentUSA

  • Simpson offers subject matter expertise and former antitrust enforcement experience.

    Antitrust respondentUSA

  • Simpson Thacher demonstrate expertise and knowledge about the business. They are proficient at navigating complex and sophisticated matters.

    Antitrust respondentUSA

  • Simpson has excellent relationships among the plaintiff bar as well as the US Attorneys Office. It has excellent analytical and writing skills.

    Antitrust respondentUSA

  • The Simpson antitrust team stands out for its substantive legal knowledge and strategy.

    Antitrust respondentUSA

Notable Practitioners

Provided by Chambers

  • Sara Razi
    Sara Razi

    Sara Razi

    Sara Razi is the co-chair of the firm's antitrust and trade regulation practice. She leverages previous government experience at the FTC when advising clients on mergers, litigation and investigations.

    • Sara is a sharp, strategic lawyer. She handled a tough situation extremely well.

      Antitrust respondentUSA

    • Sara is a smart antitrust lawyer.

      Antitrust respondentUSA

    • Sara is extremely knowledgeable and can really articulate what the government will do or think. She is tremendous in litigation.

      Antitrust respondentUSA
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  • Karen Kazmerzak
    Karen Kazmerzak

    Karen Kazmerzak

    Karen Kazmerzak is recommended for her expertise in transactional antitrust matters, providing compliance counseling to prominent clients. She also handles the merger review process, notably representing third-party clients.

    • Karen is a sharp antitrust lawyer. She is really good at articulating the nuances to the business folks.

      Antitrust respondentUSA
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  • Abram J Ellis
    Abram J Ellis

    Abram J Ellis

    Abram Ellis combines his regulatory knowledge and litigation capabilities to shepherd clients through antitrust issues including merger clearance challenges and class actions.

    • Abram is very strategic, thorough and organized.

      Antitrust respondentUSA

    • Abram provides excellent service and sophistication. He is extremely responsive.

      Antitrust respondentUSA

    • Abram has the ability to take complex litigation issues and provide very easy-to-understand summaries. He provides practical advice and recommendations with excellent rationale.

      Antitrust respondentUSA

    • Abram is a real specialist and a creative thinker. He has very good advocacy and superior knowledge of antitrust law.

      Antitrust respondentUSA
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  • Preston Miller
    Preston Miller

    Preston Miller

    Preston Miller is noted for his handling of sophisticated corporate transactions. He regularly works with healthcare, manufacturing and investment companies.

    • Preston is a phenomenal lawyer.

      Antitrust respondentUSA
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Ranked Individuals at Simpson Thacher & Bartlett LLP (4)

District of Columbia

Members

Provided by Simpson Thacher & Bartlett LLP

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