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.

This news story was originally published on the firm’s website.