Anthropic Signs for 484K SF at Blackstone JV San Francisco Buildings

Anthropic is joining in on San Francisco's artificial intelligence wave that's fueling the city's recovery. The AI firm has signed a lease to occupy the full office sites at 300 Howard and 342 Howard, which combine for a total of 484,000 square feet.

The 300 Howard tower stands 25 stories and totals 466,000 square feet, while 342 Howard spans 18,000 square feet. Blackstone Real Estate and DivcoWest are the owners of both properties through a joint venture.

Additionally, the deal by Anthropic represents one of the biggest leases in San Francisco's history.

The city is coming off a notable 2025 in terms of office demand and it's almost all thanks to the tech sector's resilience. In fact, the AI sector leased2.5 million square feet in San Francisco, the highest total since 2018, according to a recent report from CBRE. Also, AI companies accounted for 82% (1.8 million square feet) of the 2.2 million square feet of net absorption in 2025. The AI trend, along with a more attractive political landscape and increasing interest from institutional equity and lenders, should continue to drive improvement.

"The AI revolution is powering San Francisco's recovery, driving demand and office utilization," David Levine, head of Blackstone Real Estate Americas, said in a statement.

"We are long-term believers in the city and look forward to supporting Anthropic's continued growth with a modernized, Class A workspace in this prime submarket."

The 300 Howard building also features 13,000 square feet of retail space and sits near Salesforce Park, which takes up four blocks and five acres.

The two leases add to Anthropic's existing occupancy presence on Howard Street, which includes 500 and 505 Howard.