A long-vacant SoMa office building that has been gathering dust instead of tenants is finally getting a new life. Flux, an AI-focused hardware and design startup, is moving its San Francisco headquarters into 340 Bryant Street, a four-story property that has been empty since it changed hands late last year. The deal drops another AI pin on the map in a corridor already being reshaped by the sector from SoMa to the Embarcadero.
According to CoStar, Flux has signed on as the anchor tenant at the roughly 66,000-square-foot building, which had sat unused after its sale. Newmark brokers Mark Geisreiter and Charlie Withers are listed as contacts on the property, and while the lease terms and target move-in date are not being disclosed, the commitment effectively turns an idle asset into a new AI hub.
Who Bought the Building and Why
REALM, in partnership with investment firm Cannae Partners, picked up 340 Bryant in late 2025 for about $10 million, according to a press release from REALM. The four-story building dates back to 1932 and underwent a major renovation in 2015, with roughly $14.7 million in improvements that updated its systems and layout.
REALM has pitched the property as especially suitable for technology, AI and R&D tenants, citing its flexible MUO zoning and rooftop deck as key selling points. In the release, the firm said, “340 Bryant represents perfectly what we look for in an attractive investment,” pointing to modern systems and flexible floor plates. The acquisition was framed as a way to capture upside through lease-up to AI and R&D users, according to REALM. Flux, for its part, describes itself on its website as a browser-based, AI-assisted PCB and hardware design platform.
Why an AI Tenant Matters for San Francisco
The Flux deal slots neatly into a broader pattern that has been hard to miss in San Francisco’s office market. AI companies have been snapping up space at a clip that has surprised even seasoned brokers and analysts, helping certain submarkets stabilize faster than many expected.
The Real Deal reports that AI tenants accounted for roughly 2.5 million square feet of leasing last year. Meanwhile, SFGATE has highlighted marquee transactions such as Anthropic’s takeover of 300 Howard as evidence that the right kind of office, in the right location, can still draw serious demand.
Flux’s move into 340 Bryant ticks several of those boxes. The property gives an emerging AI player room to grow, while offering the ownership group exactly the kind of tenant it had in mind when it bought and repositioned the building.
Building Basics and Next Steps
Public listings peg the building at roughly 65,718 square feet with MUO zoning, exposed ceilings, showers and a rooftop deck, all features brokers say appeal to small but fast-growing AI teams. The details are laid out on CityFeet, along with a broker listing on LoopNet. Flux’s exact square footage and its target timing for occupancy have not been disclosed publicly.
Local brokers say the Flux lease is an encouraging example of the kind of smaller, full-building deal that could help older SoMa office stock find its footing again. If Flux ultimately takes a significant share of the space, the move would bring fresh activity to the Second Street corridor between downtown, Oracle Park and the Chase Center, an area where landlords have been eager to see more lights on at night.
