OpenAI Mountain View Campus Lease Confirmed

OpenAI isn’t letting up on its Bay Area expansion spree.

After months of speculation about growing into Silicon Valley, KKR Real Estate Finance Trust and TMG Partners confirmed the Sam Altman-led firm leased a five-building, 450,000-square-foot office campus in Mountain View, the San Francisco Business Times reported.

Goldman Sachs and TMG Partners acquired the offices at 350-380 Ellis Street during the pandemic, but in 2024, the firms returned the deed-in-lieu of foreclosure to KKR Real Estate Finance Trust, according to the Business Times. TMG still leases and manages 350-380 Ellis on behalf of KKR and spearheaded a renovation effort that added a new cafe, rooftop decks and a 2-acre amenity area including a tennis court, a sand volleyball court and outdoor workspace. The property was once the headquarters for cybersecurity firm NortonLifeLock, formerly known as Symantec.

The expansion into Silicon Valley comes in the wake of OpenAI’s growth spurt in San Francisco. Earlier this month, the artificial intelligence giant completed a deal to sublease approximately 280,000 square feet of office space at 1800 Owens Street, the former headquarters complex for Dropbox. That lease brought OpenAI’s total office footprint in San Francisco to over 1 million square feet, all in Mission Bay.

In 2024, the artificial intelligence giant inked a full-building sublease with Gap spanning 315,000 square feet at 550 Terry A. Francois Boulevard in Mission Bay. That deal followed a 2023 sublease with Uber to occupy two buildings at 1455 and 1515 Third Street.

AI’s foothold in the Bay Area has been creeping out of San Francisco in recent years. AI companies now occupy at least 6 million square feet across Silicon Valley, according to the Business Times. Databricks’ latest 180,400-square-foot expansion in Sunnyvale ranks among the largest leases recently signed.

Overall, the Silicon Valley office market appears to be emerging from post-pandemic lows. Vacancy fell to 16.1 percent at the end of last year, according to CBRE’s fourth quarter report for the region. The 508,000 square feet of net absorption in the fourth quarter was largely driven by AI and tech tenants, per the Business Times.— Chris Malone Méndez