Thinking Machines Lab has signed its first East Coast office lease, taking the entire fourth floor of the building at 79 Fifth Avenue near Union Square. The San Francisco-based artificial intelligence research startup, founded by former OpenAI Chief Technology Officer Mira Murati, inked a deal for 21,500 square feet in the 18-story property.
The lease was first reported by CoStar, which noted the new footprint marks the company's inaugural office on the East Coast. Thinking Machines Lab was founded in February 2025 in San Francisco by Murati and chief scientist John Schulman as a public benefit corporation, according to Wikipedia, which notes Murati previously served as OpenAI's CTO and briefly stepped in as the company's interim CEO in late 2023.
The Manhattan deal was negotiated by JLL brokers Justin Haber and Kyle Riker on behalf of Thinking Machines Lab, while Newmark brokers David Falk, Daniel Levine, and Dylan Weisman represented A&R Kalimian Realty LP. Asking rents at 79 Fifth Avenue reportedly hover slightly above $100 per square foot as of August.
A Growing Roster of Union Square Neighbors
Thinking Machines Lab will share the building with an eclectic mix of tenants, including streaming service Hulu, clothing retailer Free People, and The New School. The building's tenants also include consulting firm Capgemini America.
The New York expansion follows a much larger real estate move out west. Thinking Machines Lab leased an entire 72,500-square-foot building at 2300 Harrison Street in San Francisco's Mission District in August 2025 to serve as its corporate headquarters. The San Francisco lease preceded the Manhattan expansion.
Backed by a Record-Setting War Chest
The office expansion comes on the heels of extraordinary financial backing. In July 2025, Thinking Machines Lab completed a $2 billion seed funding round led by Andreessen Horowitz at a $12 billion valuation, with participation from Nvidia, AMD, Cisco, and Jane Street, according to MLQ.ai, which describes the round as the largest seed financing in venture capital history. A year later, in July 2026, the company released Inkling, a 975-billion-parameter open-weight model; Tinker is an API for fine-tuning open-weight models.
Manhattan's AI Office Boom
Thinking Machines Lab's move is part of a broader surge reshaping Manhattan's commercial real estate market. Technology companies have been active in New York City office leasing, while AI companies have contributed to Manhattan's tech-office activity.
Much of that activity has concentrated in the Midtown South submarket, where 79 Fifth Avenue sits. The area captured 75.1% of all tech office leasing in Manhattan during the first half of 2026, with AI companies leasing 1.5 million square feet across 63 deals, Hoodline previously reported, noting that asking rents in Midtown South averaged $85.73 per square foot in the second quarter of 2026. The trend was on display again this week, as another AI-focused startup, Orbital plants its flag in the nearby Flatiron District. How quickly Thinking Machines Lab plans to staff up its new Manhattan floor, and whether further East Coast expansions are in the works, remains unclear.
