Overview
Mark D. Nielsen brings extensive experience as a senior legal leader and former public company executive at a large, publicly traded telecommunications company, where he served as Chief Legal Officer and General Counsel overseeing complex legal, regulatory, and business matters. He also has significant experience in government, having held senior legal and policy roles at the state level.
From 2014 to 2026, Mark served as Chief Legal Officer of Frontier Communications (NASDAQ: FYBR), a national telecommunications company, with responsibility for all corporate, litigation, contractual, intellectual property, and employment matters, as well as all state and federal regulatory affairs. He concluded his tenure with Frontier in connection with the successful closing of the company's $22 billion sale to Verizon.
Prior to joining Frontier, Mark served as Associate General Counsel of Praxair, Inc. (2009 – 2014) and Assistant General Counsel of Raytheon Company (2007 – 2009).
From 2004 to 2007, Mark served under Massachusetts Governor Mitt Romney, first as Chief Legal Counsel and subsequently as Chief of Staff. As Chief Legal Counsel, he advised on legal implications of policy decisions, drafted legislation and executive orders, and served as the Governor's principal advisor on judicial appointments. As Chief of Staff, he was responsible for the Administration's policy and legislative agenda and oversaw the day-to-day operations of state government.
Earlier in his career, Mark served as an elected member of the Connecticut Legislature, serving as state representative (1993-1995) and then state senator (1995-1999). He began his legal career as a law clerk to Justice Neil L. Lynch of the Massachusetts Supreme Judicial Court (1989-1990).
Mark is currently a member of the Adjunct Faculty at Columbia Law School. He teaches a popular class on the in-house practice of law.
Experience
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Oversaw all legal aspects of multiple multi-billion-dollar plus M&A transactions
Obtained numerous state and federal regulatory approvals required for the completion of various large and complex M&A transactions
Managed a nationwide litigation portfolio involving contract disputes, consumer class actions, regulatory enforcement matters, and other high-stakes commercial litigation
Served as Chief Restructuring Officer in connection with a large court-assisted balance sheet restructuring
Advised boards of directors and senior executives on a wide variety of matters relating to corporate governance, legal compliance, and litigation risk
Oversaw internal investigations involving compliance, ethics, and potential regulatory enforcement
Led the legal response to a major shareholder activist campaign
Education and Credentials
Education
- Harvard Law School, J.D., cum laude, 1989
- Harvard University, A.B., magna cum laude, 1986
Admissions
- State of Connecticut
- State of New York
- Commonwealth of Massachusetts