Former Public Company Executive Mark Nielsen Joins Day Pitney

Brings Blue-Chip Corporate & Public Sector Experience

Day Pitney LLP is pleased to announce that Mark Nielsen has joined the firm as Of Counsel in the Corporate and Business Law Department, bringing his considerable experience in top in-house legal roles including nearly 12 years as chief legal officer of Frontier Communications and, earlier, chief counsel and chief of staff to then-Massachusetts Governor Mitt Romney. He will be based in the firm’s Stamford, Connecticut office. 

“We are fortunate to bring someone with Mark’s distinguished depth and breadth of experience to serve our clients and strengthen our firm across our locations and practices,” said Gregory A. Hayes, Day Pitney’s Managing Partner. “For nearly two decades, Mark served as a senior in-house legal leader at major public companies giving him a unique understanding of the challenges our clients face, from navigating highly regulated industries and government oversight to guiding companies through complex transactions, restructurings, and transformational business decisions. Just as importantly, Mark brings senior public-sector experience. Earlier in his career, Mark served as a respected and influential state lawmaker in Connecticut and, later, as the top advisor to Massachusetts Governor Mitt Romney. His perspective will be invaluable to our clients and will complement our corporate, regulatory, and restructuring practices.” 

Nielsen comes to Day Pitney on the heels of the January 2026 closing of Frontier’s sale to Verizon for $22 billion in cash and assumed debt.  At Frontier, he steered the company through four multi-billion-dollar M&A transactions, a myriad of high-stakes court cases, a shareholder activist campaign, three CEO transitions, and a $17 billion bankruptcy restructuring leading to the company’s operational turnaround.

As an honors graduate of Harvard College and Harvard Law School, Nielsen has held a series of senior in-house legal roles for nearly 20 years at Raytheon, Praxair, and Frontier. 

From 2004 to 2007, Nielsen served as chief legal counsel and, later, chief of staff to Massachusetts Governor Mitt Romney. As chief counsel, he provided advice on legal aspects of policy decisions, drafted legislation and executive orders, and served as Romney’s principal advisor on judicial appointments. As chief of staff, Nielsen was responsible for the Romney Administration’s policy and legislative initiatives and for overseeing the daily operations of the state government.

In his own right, Nielsen was elected to the Connecticut House of Representatives in 1992 and to two terms in the state Senate in 1994 and 1996, representing the greater Danbury area. He currently resides in Ridgefield. 

Nielsen commented, “As I looked to the next stage in my career, I was drawn to Day Pitney because of the firm’s strong reputation for strategic counsel, client service, and collaborative culture. Having spent much of my career inside large organizations navigating regulatory complexity, transformational transactions, and high-stakes business decisions, I look forward to helping clients anticipate challenges and execute on their most important initiatives. Day Pitney’s collaborative platform and deep experience across industries make it an ideal place to continue advising companies and leadership teams on the issues that matter most to their businesses.”

Drawing on his experience as both a senior in-house executive and public official, Nielsen will work with Day Pitney attorneys across practices to help clients navigate complex regulatory environments, large-scale transactions, restructurings, and strategic corporate initiatives. 

In addition to his distinguished career in the public and private sectors, Nielsen is a member of the Adjunct Faculty at Columbia Law School. He is admitted to practice in Connecticut, Massachusetts, and New York.

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