OpenAI Subleases 280,000 Square Feet at Former Dropbox HQ in Mission Bay

OpenAI has subleased roughly 280,000 square feet at the former Dropbox headquarters complex at 1800 Owens St. in Mission Bay, a deal that, combined with its existing holdings, pushes the company's San Francisco office footprint past 1 million square feet and cements its standing as the city's fastest-growing office tenant in recent years.

The transaction adds to an already substantial Mission Bay presence. OpenAI had previously taken over 800,000 square feet across three buildings in the neighborhood, a figure that includes 486,600 square feet at Uber's four-building headquarters campus, where OpenAI is leasing two buildings from the ride-hailing company as Uber right-sizes its real estate. An Uber spokesperson confirmed that deal had closed. Because both transactions are subleases, landlords were required to give consent, a process that lengthened negotiations.

The 1800 Owens St. complex has a complicated recent history. NortonLifeLock previously occupied the five-building site before selling it in 2021 to TMG Partners and Goldman Sachs for $357.6 million. KKR, which had been the lender on that deal, foreclosed on the buildings in 2024 and took ownership. What OpenAI is paying in rent is not clear, though Cushman & Wakefield's annual asking rent data puts San Francisco office space at $67.47 per square foot, compared to $74.88 per square foot in Mountain View.

The deal, which Fortune characterized as the largest office lease in San Francisco since 2018, arrives against a backdrop of a stubbornly weak local office market. San Francisco's vacancy rate stood at 33.1% at the end of 2025, according to Cushman & Wakefield, more than thirteen percentage points above Silicon Valley's 19.4% rate over the same period. Office attendance in large cities remains roughly half of 2019 levels, according to the Wall Street Journal. OpenAI CEO Sam Altman has publicly pushed back against that trend, dismissing fully remote work as one of the tech industry's worst mistakes and emphasizing the value of in-office collaboration.

OpenAI's expansion is accelerating a broader transformation of Mission Bay, a neighborhood historically anchored by life sciences and biotech tenants. The company's gravitational pull is drawing AI startups seeking proximity to talent, modern campuses, and shared infrastructure. Google already maintains secondary offices on the same block as OpenAI's new 1800 Owens St. location, and the site sits just miles from Microsoft's offices and Google's primary headquarters.

That clustering extends into neighboring Showplace Square, just west of Mission Bay across Highway 101. Together AI is in talks to lease 150,000 square feet at 2 Henry Adams St., while Physical Intelligence is nearing a deal for roughly 60,000 square feet at 808 Brannan St., a building being marketed as a sublease by Airbnb. Scale AI subleased approximately 175,000 square feet at 650 Townsend St. in 2024 under a similar arrangement. Elsewhere in the city, Hive AI leased 57,117 square feet in a downtown skyscraper adjacent to Salesforce Tower, Hayden AI took 41,196 square feet, Anthropic 17,735, and Tome AI 16,887, bringing the combined AI leasing total across five companies, including OpenAI, to nearly 620,000 square feet citywide.

OpenAI did not immediately respond to a request for comment.