Since late 2025, Olmstead Properties and investment platform Vertex have been on a leasing tear in the Flatiron area, locking in more than 67,000 square feet across 373 and 381 Park Avenue South. Residential brokerage heavyweight the Corcoran Group has committed to a full floor at 381, while AI startup Stuut grabbed the entire fifth floor at 373 and was already up and running as 2026 kicked off. The quick succession of deals is giving fresh evidence that well-located, boutique office buildings can still draw tenants when prewar character comes packaged with turnkey, move-in-ready space.
Corcoran signed an 11-year lease for 14,710 square feet, taking the entire third floor at 381 Park Avenue South and planning a move from its current home at 387 Park Avenue South, with occupancy expected in summer 2026, as reported by Commercial Observer. Corcoran’s Paul Wexler represented the brokerage in-house, while Olmstead's Steven Marvin and Jonathan Bock negotiated on behalf of the landlord.
Altogether, Olmstead and Vertex have lined up more than 67,000 square feet of leases across the two Park Avenue South properties as they launch a broader repositioning play in the Flatiron district, according to the New York Real Estate Journal. The outlet reports that nine additional deals add up to about 43,000 square feet, and ownership has roughly 15,000 square feet currently out for signature.
Owners Race To Deliver Turnkey Space
Olmstead picked up both buildings from ATCO Properties in November 2025 in a deal industry sources pegged at about $104 million, and has zeroed in on upgrades to lure tenants further downtown, per The Real Deal. The pair fits squarely into the classic Midtown South prewar mold: 381 Park Avenue South rises 17 stories and spans about 244,000 square feet, while 373 stands 12 stories tall with approximately 112,000 square feet.
AI firm Stuut opted for a short-term lease covering 9,043 square feet, taking the full fifth floor at 373 Park Avenue South and beginning occupancy on January 1, 2026, the New York Real Estate Journal reports. CEO Tarek Alaruri told the outlet the company moved from initial offer to fully executed lease in three weeks and completed its relocation over the holidays, crediting Olmstead's speed and professionalism for making the tight timeline work.
What It Means For Midtown South
To keep that kind of momentum going, ownership has rolled out four newly built prebuilt suites ranging from about 3,200 to 6,500 square feet and tapped COOKFOX Architects to revamp the lobbies, common areas and elevators, with delivery expected later in 2026, according to Commercial Observer. Brokers say those smaller, polished, plug-and-play spaces are exactly what tech, media and professional services outfits are hunting for near Madison Square Park, where speed to occupancy can be as important as the view.
The next test is whether Olmstead can turn its active pipeline into fully signed leases and land a new ground-floor retail tenant for a storefront that drew multiple offers after the prior operator departed. As The Real Deal notes, Olmstead's managing director called the pair of buildings “quintessential Olmstead buildings - classic architecture, prime location and untapped potential,” a line that neatly sums up the landlord’s bet that historic bones plus modern upgrades can still punch above their weight in Midtown South.
