Breno Vieira

Senior Manager


  • Chicago


Breno Vieira addresses complex antitrust and competition issues arising in the digital entertainment, gaming, healthcare, and telecommunications industries. Dr. Vieira specializes in merger review, with a focus on matters involving market definition, market power, and industrial organization. He leads large teams working with attorneys throughout the litigation process, and supports experts through discovery and trial.

Tech and big data

Dr. Vieira has managed complex, data-intensive matters requiring customized big data servers and analytical methods. He has substantial experience with proprietary and public datasets involving billions of records.


Dr. Vieira has experience in all phases of merger review, including evaluating market definition and assessing the impact of mergers, divestitures, and content creation incentives. He has analyzed complex organizations with vertical and horizontal integration components, applied sophisticated modeling techniques to assess substitution between products, and evaluated post-merger incentives. Dr. Vieira’s experience includes:

  • T-Mobile/Sprint: Assisted with the regulatory review of T-Mobile’s $26 billion merger with Sprint, supporting experts to analyze how consumers choose wireless carriers and how wireless carriers compete.
  • United States v. AT&T Inc. et al.: Supported experts in rebutting market research studies used to predict potential subscriber loss and to form a measure of harm.
  • Proposed Merger of Aetna and Humana Enjoined: Supported testifying experts in their analyses and rebuttal critiques of relevant market, competitive effects, and demand estimation issues.
Antitrust and competition

Dr. Vieira has assessed class certification, liability, and damages issues in a range of matters involving allegations of monopolization and tying. He has particular expertise with matters in the media, telecommunications, and technology industries. His experience includes:

  • Evaluating demand and competition using proprietary, transaction-level datasets to assess competition between platforms.
  • Applying complex structural models to assess companies’ market definition and post-merger incentives.

Efficiencies Defense in the Spotlight After T-Mobile/Sprint Ruling


T-Mobile/Sprint Merger Approved


United States v. AT&T Inc. et al.


Proposed Merger of Aetna and Humana Enjoined