Image courtesy of SGA

A long-coveted Kendall Square tech office appears to be under agreement to be occupied by Facebook, expanding its presence in the Cambridge tech hub by at least 263,000 square feet.

The social media giant is set to sublease the space at 50 Binney St. from Cambridge-based Bluebird Bio, tripling its local office space, according to a real estate industry source. The complex is owned by life science developer Alexandria Real Estate Equities.

In April 2019, Bluebird Bio struck a deal to sublease the offices from original tenant Sanofi Genzyme, agreeing to pay $99.95 per square foot in rent for the offices, with a term running from July 2021 through December 2030. But it put the space on the sublease market before occupancy amid delays in FDA approval of its drug pipeline.

Facebook, meanwhile, launched a search in spring 2020 for up to 350,000 square feet of additional office space in the Cambridge area. That search appears to have ended next to its existing Kendall Square offices at 100 Binney St., where Facebook already occupies 130,000 square feet.

Both properties are part of the 2.4 million-square-foot Alexandria Center at Kendall Square portfolio, which comprises 10 buildings occupied by a who’s who of tech and life science companies.

Facebook declined to comment beyond a statement that it’s “constantly explore our real estate options in the cities where we have large offices.” The Menlo Park, California tech leader opened its first local office in 2013 at One Broadway in Cambridge.

Along with its 10-million-square-foot SIlicon Valley headquarters, Facebook had offices in more than 80 cities globally as of Dec. 31.

Editor’s note: This report has been updated with a statement from Facebook.