October 2026 Boston Office Report

Total Vacancy: 18.5%

 Total Inventory: 227.2 Million SF

Asking Rent: $46.81/SF (Average for Boston, Cambridge and Suburbs)

BOSTON

• In Back Bay, availability has fallen while the vacancy rate has remained stable throughout 2026 at 14.2%.

• Leasing activity was relatively robust – the most notable transaction was Paul Hastings leasing 52,340 SF at 888 Boylston Street. The rapidly growing law firm recently leased 15,034 SF at another BXP property, 200 Clarendon, in late 2024, and this latest signing represents a 248% expansion of their footprint.

• In the Seaport, availability rose to 27.9%, and vacancy to 24.2%. Fundamentals were impaired mostly as a function of the addition of sublease space at 1 Boston Wharf Road. Amazon has listed 375,000 SF on the upper floors of the building as available for occupancy in January.

• In Fenway, availability has dropped to 12.7% from 18.8% at the start of the year. This is largely a function of Fenway Sports Group signing for 100,500 SF at 1325 Boylston Street.

• Whoop has also leased 107,000 SF at Related Beal’s 660 Beacon Street, nearly doubling the size of their headquarters. Prior to this signing, Related had been marketing the asset as a potential lab opportunity.

SUBURBS

• After showing modest improvement in 2025, Route 128 North fundamentals have deteriorated throughout 2026 with more than 2,000,000 SF now available for lease.

• Route 128 West has made significant strides YoY – the availability rate has dropped 175 basis points from this time last year. Fundamental improvements are mostly attributable to Panera leasing 101,000 SF at 133 Boston Post Road in Weston, as well as Boston Dynamics executing a new lease in late June for 322,000 SF at 1601 Trapelo Road in Waltham. BXP has also acquired several vacant office properties, which they intend to convert to residential use.

• In the 495 West submarket – fundamentals improved due to the removal of 282,028 SF of office space at 25 Research Drive in Westborough. Alexandria Real Estate Equities had planned to redevelop the site into a life science campus when they acquired the asset in 2023, but those plans stalled as speculative space continued to deliver vacant. The property is currently on the market, and the town is having conversations with several developers to determine the future of the site.

CAMBRIDGE

• The city has seen minimal activity throughout 2026, although there has been a burst of AI office leasing in recent months.

• The total availability rate is at 27.2% – a 119 basis point increase since the close of 2025.

• East Cambridge has recorded the largest new office lease this quarter. Blitzy, an AI company that develops autonomous software, executed a 52,000 SF lease at One Kendall Square. Furthermore, Anthropic signed for 24,000 SF, also at One Kendall Square. At University Park, Toyata’s robotics spinout, Walden Robotics, inked a 50,000 SF lease at the BioMed Realty campus. These three leases are the latest examples of AI companies, rather than biotech firms, driving new office demand in Cambridge.

• Mid & West Cambridge have recorded marginal activity: there has been minimal tenant turnover, few move-outs, and limited new leasing activity.

• 40 Thorndike Street sold for a significant discount (Brookfield assumed the balance of the remaining $232 million construction loan). New sponsorship should be able to offer more compelling rental rates and concessions to jump start leasing at one of the city’s most premium pure office assets.

• Two notable office to residential conversions have been proposed this quarter. Tourbineau Real Estate Partners acquired 955 Massachusetts Avenue in Mid-Cambridge for $25,000,000 in late September. They have proposed transforming the 93,000 SF office building into 125-150 residential units. Additionally, Alexandria Real Estate Equities has proposed transforming 161 First Street in East Cambridge into affordable housing. This is a larger play by Alexandria: they want to transfer development rights from the First Street asset to allow for an additional 250,000 SF of new development at their Technology Square campus.

For more information please contact:

Mark Fallon, Director of Research & Strategy | mfallon@hunnemanre.com