Mark G. Weiss

Biography

Mark Weiss is a partner in the Firm's North America Antitrust & Competition Practice Group and the North American Chair of the Practice’s Litigation Task Force.

He is a seasoned litigator with deep expertise in antitrust, class action, and federal multi-district litigation and represents clients in high-stakes disputes across a range of industries, with a focus on complex commercial and competition-related claims. Mark defends clients in nationwide class actions and seamlessly navigates the procedural and strategic challenges of MDLs in federal court.

Mark’s is also a highly regarded criminal antitrust attorney with significant experience representing clients in complex cartel investigations and enforcement actions. Mark has a strong track record advising corporations and executives in high-stakes matters involving the U.S. Department of Justice’s Antitrust Division, particularly in cases involving leniency and cooperation strategies. He has a deep understanding of the leniency program and is a trusted advisor in navigating cross-border investigations.

Mark also has extensive experience as a leading antitrust merger attorney and has led numerous clients through complex regulatory reviews and merger clearance processes. He advises on all aspects of pre-merger strategy, including Hart-Scott-Rodino (HSR) filings, competitive risk assessments, and engagement with the Federal Trade Commission and Department of Justice.

Mark advises clients on a wide range of antitrust compliance issues, helping companies design and implement effective compliance programs tailored to their business operations and risk profiles. Mark is an expert in handling matters consistent with recent antitrust trends including artificial intelligence, algorithmic pricing, information-sharing, and both vertical and horizontal practices. He regularly conducts internal audits, risk assessments, and training for legal and business teams, and provides strategic guidance on interactions with competitors, pricing practices, and distribution arrangements.

Practice Focus

Mark's practice focuses on antitrust litigation, both private and public. He assists clients in the defense of class actions, complex civil and criminal investigations, merger challenges, and compliance counseling. He helps clients navigate federal and state regulatory inquiries, enforcement actions and multidistrict antitrust class actions.

Representative Legal Matters

Lead counsel for a multinational specialty construction chemicals company in In re: Concrete and Cement Additives Antitrust Litigation (MDL 3097) in the Southern District of New York alleging collusion and price-fixing claims.
Advised a major luxury fashion brand in litigation filed in the Northern District of California alleging anti-competitive licensing deals and monopolization claims. The client was voluntarily dismissed by plaintiffs.
Advised a global shipping company in a DOJ criminal antitrust investigation. The matter closed without action.
Drafted a Supreme Court amicus brief for the International Franchise Association in the McDonald’s v. Deslandes no-poach litigation.
Drafted amicus briefs in high stakes technology litigations including DOJ v. Google and Epic v. Apple on behalf of ACT | The App Association, a global trade association for small and medium-sized technology companies.
Advised a company before the Department of Justice Antitrust Division and assisted with obtaining conditional leniency in a many-year investigation.
Represented a major luxury fashion brand against a no poach class action. Defendants’ motion to dismiss was granted and the Second Circuit affirmed.
Defended a Japanese suspension assemblies manufacturer in In re: Hard Disk Drive Suspension Assemblies Antitrust Litigation (MDL 2918) in the Northern District of California alleging price-fixing claims.
Advised Rio Tinto on its approximately USD 700 million acquisition of a secondary aluminum manufacturing company.
Advised Cadence Design Systems, Inc. on its acquisition of Intrinsix Corp., a semiconductor design services firm, in a USD 35 million acquisition.

Admissions

District of Columbia~United States (2014)
Virginia~United States (2013)
U.S. District Court, Eastern District of Virginia
U.S. Court of Appeals, Fourth Circuit~United States
U.S. Court of Appeals, Ninth Circuit~United States

Education

George Mason University School of Law (JD, magna cum laude) (2013)
Claremont McKenna College (BA, Economics & Government) (2007)

Languages

English

Co-author, “Algorithmic Collusion and Criminal Antitrust: A Snapshot of the Current Landscape and Key Compliance Considerations,” Criminal Justice Magazine, Winter 2025
Panelist, “Corporate Compliance in the Second Trump Administration,” ABA Corp. Compliance Program, May 9, 2025
Co-author, “Trump Removes Democratic Commissioners Bedoya and Slaughter at the FTC,” Baker McKenzie Client Alert, Mar. 20, 2025
Co-author, “New Executive Orders Seek White House Control of Independent Federal Regulatory Agencies,” LexisNexis Practical Guidance & Baker McKenzie Client Alert, March 5, 2025
Co-author, “FTC Sues Southern Glazer's Wine and Spirits for Price Discrimination in its First Robinson-Patman Act Lawsuit in Over Two Decades," Baker McKenzie Client Alert, Dec. 17, 2024
Co-author, “US agencies increase coordination and use of technology to investigate data misconduct,” Baker McKenzie Client Alert, June 5, 2024