partner

900 G Street, NW
Washington, D.C. 20001

+1 202 636 5822

40 & Under List


Practice area:

Competition/antitrust


Preston Miller, a Partner in Simpson Thacher’s Washington, D.C. office, focuses his practice on antitrust and competition law. With a particular emphasis on merger review, he has extensive experience obtaining regulatory clearance from domestic and international competition authorities for high-profile, often cross-border, transactions across a wide variety of industries. He is recognized by The Legal 500 U.S. in Antitrust: Merger Control, where sources describe him as “such a strong lawyer that partners from other firms routinely acknowledge the benefits of having him on the other side as someone who will be efficient, practical, friendly and able to lead a very strong case.” He was also named a 2022 “Rising Star” by IFLR Americas. Preston also has experience in defending clients in complex class action antitrust litigation and government antitrust investigations.


Preston represents a mix of both private equity and corporate clients, having done extensive work for private equity firms like Blackstone and KKR, as well as dozens of strategic clients active in a wide range of sectors, including industrial (Gardner Denver), automotive (ZF/TRW; BorgWarner), life sciences/healthcare (CSL; Certara; Change Healthcare; HCA), defense (L3Harris), retail (Office Depot; Mattress Firm Group), semiconductors (Siltronic; Kokusai Electric), and more.


His key matters include:

  • Change Healthcare in its $13.8 billion acquisition by UnitedHealth Group, which was named “Merger Control Matter of the Year – Americas” at Global Competition Review’s GCR Awards 2023
  • Siltronic in achieving U.S. clearance of its proposed $5.3 billion acquisition by GlobalWafers, following a Second Request
  • L3 Technologies in connection with the antitrust review of its $33.5 billion merger of equals combination with Harris Corporation, including the successful divestiture of assets to resolve concerns
  • BorgWarner in its $3.3 billion acquisition of Delphi Technologies
  • Daimler and Chrysler’s formation of a mobility services joint venture, including coordination of responses to Second Requests issued to both parties
  • Melrose Industries’ takeover of public company GKN for £8 billion, in the biggest U.K. hostile takeover since 2009
  • Office Depot, in its proposed acquisition by Staples, including responding to an FTC Second Request and subsequent merger litigation


Preston was a featured speaker at Global Competition Review’s Telecoms, Media & Technology 2022 conference on the panel titled, “Breaking down the walled garden: the limits of antitrust?” He has been quoted in media outlets such as Law360 and CFTN. He earned his J.D., magna cum laude, from Georgetown University Law Center and his B.S. in Cellular and Molecular Biology and Genetics and B.A. in Philosophy from University of Maryland. He is admitted to practice in Washington, D.C. and New York.


Updated July 2023