New York – Sidley is pleased to announce that Mary Marks has joined Sidley’s office in New York as a partner in the firm’s Antitrust and Competition practice. She joins from Davis Polk & Wardwell LLP.
Ms. Marks focuses on analyzing U.S. and multinational transactions and obtaining clearance under the Hart-Scott-Rodino (HSR) Act and global merger control laws. She also counsels clients with respect to permissible pre-clearance and pre-closing coordination and information sharing, as well as inadvertent failures to file under the HSR Act.
“Mary is one of the leading lawyers advising clients navigating complex HSR and merger clearance-related issues,” said Brian Fahrney, Chair-elect of Sidley’s Executive Committee. “As antitrust regulatory burdens have increased significantly, her deep experience and practical approach will be a tremendous asset to our clients.”
“Mary has an excellent reputation within the antitrust bar and is a natural fit for Sidley,” said Nancy Chung, managing partner of Sidley’s New York office and a member of the firm’s Management and Executive Committees. “Many of our Antitrust and Competition lawyers have worked across the table from Mary on deals and consistently speak to her collaborative and client-centric approach.”
Her addition builds on a year of growth for Sidley’s office in New York, where ten lateral partners have already joined the firm’s M&A and Private Equity practice in 2025. It also follows a series of strategic additions to Sidley’s Antitrust and Competition practice, including Elisabetta “Betta” Righini in Brussels, and Vadim Brusser, Carrie Mahan, and Corey Roush in Washington, D.C.
Sidley’s Antitrust practice represents public and private corporations, funds, individuals, and associations in cases involving claims of price fixing, market allocation, actual or attempted monopolization, price discrimination, resale price maintenance, refusals to deal, information exchanges, improper dealer terminations, and other alleged antitrust violations. We have also litigated private and public challenges to proposed mergers and acquisitions.
The firm’s preeminent global M&A and Private Equity practice has more than 500 lawyers that are engaged in the full spectrum of public and private mergers and acquisitions and private equity transactions across a variety of industries, including energy, life sciences, sports, entertainment, healthcare, real estate, consumer products, manufacturing, transportation and logistics, infrastructure, technology, media and telecoms, financial services and insurance, and metals and mining.
Sidley is an elite global law firm. With approximately 2,300 lawyers and nearly 160 years of experience, we have established a reputation for deploying innovative legal strategies to achieve powerful results for our clients in complex transactional, restructuring, crisis management, investigation, regulatory, and litigation matters.
Our perspective and reach are truly global, supported by 21 offices strategically situated in key commercial, regulatory, and financial centers across the world. Our lawyers and business professionals, fluent in more than 75 languages, possess the cultural awareness and cross-border legal acumen needed to bring clarity to a dynamic business landscape.
Matt Messinger, Director, Public Relations, +1 312 456 4009 (Global)
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