Biogen Appreciation Statement for Retiring Board Members Nancy Leaming and Brian Posner

On behalf of the Biogen community, we want to extend our deepest appreciation to Nancy Leaming and Brian Posner for their years of extraordinary service and dedication as members of our Board of Directors. Ms. Leaming and Mr. Posner, who joined the Biogen Board of Directors in 2008, will retire from the Board at today’s Annual Meeting of Shareholders. Their contributions have been invaluable to Biogen’s growth and success in meeting its mission to patients, their families, and society.

During her tenure, Ms. Leaming served as Chair and as a member of the Board’s Audit Committee, where she demonstrated her strong leadership skills and financial acumen. Her deep experience in the healthcare and payor sector brought us uniquely informed insights and guidance into the rapidly evolving pricing environment for medicines. She played an important role in advancing Biogen’s commitment to transparency for the investment community, patients, and other key stakeholders. Throughout her distinguished career of achievement in healthcare, she has been a staunch advocate for health access and health equity, with an unwavering dedication to helping underrepresented and underserved communities.

Currently an independent consultant, Ms. Leaming previously served as the Chief Executive Officer and President of Tufts Health Plan, after also having held the positions of Chief Operating Officer and Chief Financial Officer. Prior to joining Tufts Healthcare, Ms. Leaming served as Chief Financial Officer and Chief Operating Officer at Harvard Community Health Plan IPA and Chief Financial Officer and Chief Operating Officer of Matthew Thornton Health Plan, Inc. Ms. Leaming currently serves on the Board of Rosie’s Place and is Chair of the Rosie’s Place Audit Committee. She is a former director of the public companies, Hologic, Inc. and Edgewater Technology, and of numerous nonprofit organizations including the American Red Cross of Mass Bay, the Massachusetts Taxpayers Association, the Boston Chamber of Commerce, AIM and AHIP.

Mr. Posner recently served as Chair of the Board’s Compensation Management and Development Committee. During his tenure on the Board, Mr. Posner’s support ensured the Company remained agile and competitive to deliver on Biogen’s mission to pioneer life-changing therapies for complex neuroscience diseases. His leadership has also been instrumental to Biogen’s growth to a global company serving millions of people around the world. With more than 30 years of combined experience as a Board member and senior corporate executive in the financial and biopharmaceutical industries, he has shown unwavering dedication to inspiring the next generation and has built an enduring legacy of promoting environmental, social and governance commitments.

Mr. Posner has been a private investor since March 2008 and is the founder and Managing Partner of Point Rider Group LLC, a boutique consulting and advisory services firm. From 2005 to 2008, Mr. Posner served as the President, Chief Executive Officer and co-Chief Investment Officer of ClearBridge Advisors LLC, an asset management company. Prior to that, Mr. Posner co-founded Hygrove Partners LLC, a private investment fund, in 2000 and served as its Managing Partner for five years. He served as a portfolio manager and an analyst at Fidelity Investments from 1987 to 1996 and, from 1997 to 1999, at Warburg Pincus Asset Management/Credit Suisse Asset Management, where he also served as co-Chief Investment Officer and Director of Research. Mr. Posner also serves as the Chairman of AQR Funds, an investment fund, and as a director of Arch Capital Group Ltd.

We thank Ms. Leaming and Mr. Posner for nearly 15 years of extraordinary service to Biogen and the patients we serve.