LAWYER PROFILE
Mark C Williams

Mark C Williams

Global 2026

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About

Provided by Clifford Chance US LLP

Practice Areas

Mark Williams represents clients that invest in the electric power and natural gas industries. He has advised private equity funds, insurance-sector investors, banks, pension funds, multinational institutional investors, hedge funds, and traditional investment funds on the complex regulatory requirements applicable to electricity and gas investments. He also advises on electricity and gas investments, financings, mergers, acquisitions, securities, and restructuring transactions.

Mark has represented investors in transactions totaling more than 44,000 MW of electric generating capacity, and more than 29,000 miles of natural gas pipeline capacity. He has protected the power sales eligibility and regulatory exemptions of renewable and high-efficiency Qualifying Facilities. He has advised buyers and sellers of generating company assets and interests on regulatory strategy and in formal application proceedings, and during the last decade, he has always had one or more M&A applications pending before FERC. He successfully represented private equity and insurance investors in former Enron electric facilities in FERC's 2003–2004 Enron proceedings, leading to the full and public exoneration of the clients.

Before entering private practice, Mark was the sole attorney in the Division of Corporate Applications of the Federal Energy Regulatory Commission (FERC). In that role, he advised the commission on merger, divestiture, financing, independent power, and electrical transmission system matters, and led more than 100 commission orders in transactional-regulatory matters.

Mark also led FERC's review of generation facility sales, utility and holding company restructuring transactions, and a range of Regional Transmission Organization (RTO) proposals, including the acquisition of a US utility by a foreign energy system, and the independence of RTOs from other energy market participants.

Chambers USA recognized Mark as "one of the leading attorneys in the USA when it comes to the regulatory aspects of the purchase and sale of electric generation assets" and as "a tremendous resource for any team . . . well versed in regulatory minutiae and top of the class in the regulatory space." He is also recognized by Chambers Global and has been lead energy regulatory counsel to several project finance "deals of the year."

Prior to joining Mayer Brown, Mark was a partner in the energy practice of another international law firm.

Chambers Review

Provided by Chambers

Chambers Global Guide

Energy: Electricity (Regulatory & Litigation) - USA

Band 3
Band 3

Individual Editorial
Mark Williams provides adept counsel on the regulatory elements of corporate transactions. He frequently acts for utilities, corporates and investors across the sector.

Strengths

Provided by Chambers

  • We appreciate the detailed level of his subject matter; he can tell you everything about it.

    Energy: Electricity (Regulatory & Litigation)Chambers Global Guide
  • Mark is a consummate professional who has an encyclopedic knowledge of FERC and the energy regulatory space.

    Energy: Electricity (Regulatory & Litigation)Chambers Global Guide

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