BIOGEN INC.

Below is a summary of our significant properties owned and leased as of December 31, 2025.

(1) We also lease office space in other international regions including: the U.K.; Germany; France; Japan; Canada and numerous other countries. Our international lease agreements expire at various dates through the year 2047.

In the fourth quarter of 2021 we began construction of a new clinical packaging and other manufacturing facility in RTP, North Carolina to support our R&D pipeline across multiple therapeutic areas. The new manufacturing facility is approximately 197,000 square feet. The construction of this manufacturing facility was completed during 2025 and the majority of the facility was placed in service during the fourth quarter of 2025.

In March 2025 we entered into a lease agreement with MIT Investment Management Company and BioMed Realty for the lease of approximately 580,000 square feet of office and research and development space located at 75 Broadway, Cambridge, Massachusetts, which will be used as our new global corporate headquarters, as well as integrating our research and development and technical operations teams alongside our North American commercial organization. As part of a multi-year real estate consolidation plan that is expected to result in a reduction of approximately 40% of our real estate footprint in Massachusetts, this new lease is intended to replace two existing leases, both in Cambridge, Massachusetts, including our current corporate headquarters. We expect the initial lease term of approximately 15.5 years to commence on May 31, 2028.

We believe that our existing properties, including both owned and leased sites, are adequate and suitable for the conduct of our business. We believe our capital resources are sufficient to purchase, lease or construct any additional facilities required to meet our expected long-term growth needs.