Photo courtesy of the city of Cambridge

One of Kendall Square’s dominant players just added a new property to its portfolio.

Boston Properties bought 125 Broadway in Cambridge for $602.84 million from troubled drugmaker Biogen on Sept. 16, documents filed with the South Middlesex Registry of Deeds show.

BXP said it funded the purchase price with cash and borrowings under its line of credit, and it is “evaluating opportunities to own the property with one or more joint venture equity partners.”

Biogen will still occupy the building after signing a lease that runs through April 2028. Along with the sale, Biogen will end its lease at 300 Binney St. next door – around the corner from its 225 Binney headquarters – after earlier this year announcing it would try to sublease over 183,000 square feet of its space in the building.

Boston Properties said 300 Binney would be renovated and expanded into a 240,000-square-foot lab building and said that an unspecified “prominent life sciences organization” had inked a 15-year lease for the space, which is expected to open in 2024.

Biogen has struggled since one of its flagship new drugs, Alzheimer’s treatment Aduhelm, failed to live up to its advertised potential and ran into criticisms from regulators. The company announced this summer that it was trying to cut $1 billion in costs and make an unspecified number of layoffs to tame investor fears.

“We are thrilled to complete this acquisition and continue our longstanding relationship with Biogen,” said Boston Properties Boston region Executive Vice President Bryan Koop said in a statement. “BXP has been an integral member of the Cambridge community since the development of our first property in 1981, and we are pleased to continue to grow and evolve Kendall Center to meet the needs of the life sciences community.”

The 6-story, 225,815-square-foot 125 Broadway lab building was built in 1990 and sold to Biogen in 2000 for $2.53 million.