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Debbie Feinstein heads Arnold & Porter's Global Antitrust group, and brings a wealth of experience to her practice in advising clients on a range of antitrust challenges before U.S. antitrust authorities. She re-joined the firm from the U.S. Federal Trade Commission (FTC), where she was Director of the Bureau of Competition. In that capacity, she was responsible for supervising the investigation and enforcement of the U.S. antitrust laws against anticompetitive mergers and conduct. During her tenure from 2013 to 2017, the FTC had substantial litigation success and a number of major merger wins, including challenges to Sysco Corp.'s acquisition of rival U.S. Foods Inc., and Staples Inc.'s merger with Office Depot Inc. She had previously served at the FTC from 1989 to 1991 as Assistant to the Director of the Bureau of Competition and Attorney Advisor.

Throughout her career, Debbie has focused on merger and acquisition reviews by antitrust enforcement agencies in the U.S. and globally, as well as civil investigations and litigation. Her industry experience is broad, and includes retail, food, consumer products, healthcare, chemicals, and automotive parts, among others.

Debbie has been consistently lauded as a leading practitioner by Chambers USA and other ranking publications. The National Law Journal named her one of the most influential women lawyers in America and Global Competition Review recognized her as global "Lawyer of the Year" and named her to its international list of the "Top 100 Women in Antitrust."


  • Pfizer in its $43 billion acquisition of Seagen Inc., a world-leader in antibody-drug conjugates (ADCs).
  • Wyndham Hotels & Resorts in connection with Choice Hotel’s proposed hostile takeover of Wyndham.  
  • Altria in its US$2.75 billion acquisition of NJOY Holdings Inc. 
  • Sony in numerous transactions, including its US$3.6 billion acquisition of games software developer Bungie and its US$2.2 billion acquisition of the music publishing catalogue of EMI.
  • AT&T in the numerous transactions including the merger of the WarnerMedia business with Discovery and its prior acquisition of TimeWarner.
  • Cargill and Continental Grain in their US$4.5 billion acquisition of Sanderson Farms.
  • Penguin Random House in its US$2.175 billion attempted acquisition of book publisher Simon & Schuster.
  • Thermo Fisher Scientific, Inc. in its US$21 billion purchase of PPD Inc.
  • Bristol-Myers Squibb in numerous transactions including its US$90 billion acquisition of Celgene and its US$4.1 billion acquisition of Turning Point Therapeutics.
  • Pfizer in its US$6.7 billion acquisition of Arena Pharmaceuticals.
  • AbbVie in its US$63 billion dollar acquisition of Allergan and in its US$550 million acquisition of Soliton Inc.
  • Billie in the US$310 million sale of its business to Edgewell.
  • Fitbit Inc. in its US$2.1 billion sale to Google.
  • Altria in its investment in JLI, the parent company of JUUL.
  • Reyes Holdings in the US$2 billion sale of its Reinhart FoodService business to Performance Food Group.
  • Panasonic in establishing Prime Planet Energy & Solutions, Inc., a joint venture with Toyota specializing in automatic prismatic batteries.
  • Cisco Systems, Inc. in its US$1.9 billion acquisition of BroadSoft, Inc.
  • Onex and SMG, a facility management company, in its merger with AEG Facilities to create a global facility management and venue services company.
  • Rent-a-Center in its proposed acquisition by Vintage Capital.
  • NxStage Medical, Inc. in connection with its US$2 billion sale to Fresenius Medical Care Holdings, Inc.
  • General Electric Co. in numerous transactions including the Comcast/NBCU joint venture, the US$4.3 billion acquisition of Avio, and the US$2.1 billion acquisition of Instrumentarium.
  • Boston Scientific Corporation in numerous transactions including its US$27 billion acquisition of Guidant.
  • Loews Cineplex Entertainment Corporation in its merger with AMC Entertainment Inc.
  • The Kroger Co. in its US$13.5 billion merger with Fred Meyer, Inc.
  • Phillip Morris and Kraft in their US$18.9 billion acquisition of Nabisco Holdings Corporation, creating the world's largest food company. Negotiations with the FTC resulted in the divestiture of only minimal assets.
  • Occidental Chemical Company in the US$360 million purchase of Vulcan Materials Company's chemical assets.
  • PepsiCo in its US$14 billion acquisition of The Quaker Oats Company. The merger strengthened PepsiCo's food businesses and added Gatorade, the leading sports drink brand, to its portfolio.
  • Meritor Automotive in its merger with Arvin Industries to become ArvinMeritor, a leading automotive industry supplier.
  • Genzyme's acquisition of Novazyme. The acquisition combined the only two companies performing research and development on a rare disease.
  • Unilever in the acquisition of Alberto Culver and in the sale of its Lawry's & Adolph's spice/seasonings business to McCormick.


The Legal 500 US
"Hall of Fame" Antitrust: Merger Control (2022-2024)
Antitrust: Merger Control (2019-2022)
Antitrust: Cartel (2018-2019, 2021-2022)
Antitrust: Civil Litigation/Class Action (2018-2019, 2021-2022)
"Leading Lawyer" Antitrust: Merger Control (2020-2021)
Chambers USA
Antitrust — DC (2018-2024)
Antitrust — Nationwide (2022)
Antitrust: Business (2011)
Benchmark Litigation
"Litigation Star" Competition/Antitrust (2024)



  • J.D., Harvard Law School
  • A.B., University of California, Berkeley


  • District of Columbia

Government & Military Service

  • Director of the Bureau of Competition, Federal Trade Commission (2013-2017)
  • Assistant to the Director of the Bureau of Competition and Attorney Advisor, Federal Trade Commission (1989-1991)