OpenAI leased a five-building, 450K SF office campus at 350-380 Ellis St. in Mountain View, California.

Owners KKR Real Estate Finance Trust and TMG Partners spent the past two years upgrading the campus inside and out, adding dining options and a 2-acre amenity zone that includes a tennis court and a sand volleyball court.

The redevelopment was designed to meet demand for amenity-rich offices in Silicon Valley, TMG President Ben Kochalski said in a release.

The lease is just the latest in the Bay Area for OpenAI, which has leased a few large office spaces in San Francisco in the last three years.

In 2024, the company finalized a 315K SF, full‑building lease at 550 Terry A. Francois Blvd. after taking over 486K SF at 1455 and 1515 Third St. from Uber in 2023.

Earlier this year, OpenAI signed a 280K SF sublease at 1800 Owens St., the former Dropbox headquarters, pushing its San Francisco footprint past 1M SF as artificial intelligence firms continue to drive demand.

The Silicon Valley office market is showing tentative signs of recovery. Office vacancy in the region fell to 16.1% at the end of 2025, according to CBRE. The fourth quarter's 508K SF of net absorption was largely driven by AI and tech tenants.

OpenAI’s real estate expansion mirrors the company’s breakneck operational and financial growth. The firm’s annualized revenue climbed to $25B in early 2026, up from virtually zero just three years ago.