Ken Griffin isn’t letting the prospect of a pied-à-terre tax slow his Manhattan expansion.

The Citadel founder has reportedly paid $38 million in an all cash deal for a sprawling duplex at 740 Park Avenue, adding to his stake in one of the Upper East Side’s most storied co-ops. The seller—shielded behind a trust—purchased the unit for $20.5 million in 2019, nearly doubling their investment in the latest transaction.

Beyond the building’s prestige and the apartment’s scale, the price is what stands out; Griffin paid well above where similarly sized apartments are priced, with two apartments in the building asking around $22 million. The unit reportedly underwent a multimillion-dollar renovation, but what likely drove some of the uptick in price is proximity. The roughly 7,500-square-foot residence sits directly beside another duplex Griffin acquired in early 2025 from Julia Koch, the widow of David Koch, for $45 million. 

All in, Griffin now has about $83 million tied up in the building—before any additional costs related to a merger, which could run well into the tens of millions. Those figures rival some of the biggest deals ever recorded at 740 Park Avenue. Howard and Nancy Marks paid $52.5 million for a much larger apartment back in 2012, while Israel “Izzy” Englander dropped a whopping $71.3 million on a gigantic duplex in 2014. 

The acquisition follows a familiar strategy for Griffin, who has made a habit of buying contiguous properties and stitching them together. About 12 blocks away, at 220 Central Park South, he paid a record-setting $238 million for a massive penthouse in 2019 and later added additional units in the building. He has taken a similar approach in both Miami Beach and Palm Beach, assembling roughly 25 acres of ocean-to-lakefront land in the latter that is expected to become a mega-compound potentially valued at $1 billion.

Griffin is a notorious trophy-property collector, and his vast real estate portfolio stretches across the globe. In London, a mansion near Buckingham Palace cost about $122 million, while in the Hamptons, an $84.4 million estate anchors his Southampton holdings. Since relocating his primary base to Miami in 2022, he has poured more than $275 million into properties across Coconut Grove and Star Island. Additional footholds in Aspen and Hawaii follow a familiar pattern of buying adjacent homes within the same enclave.

Designed in 1929 by Rosario Candela and developed by James T. Lee—the grandfather of Jacqueline Kennedy Onassis—740 Park Avenue has long been associated with families like the Rockefellers and ranks among the city’s most powerful and socially influential addresses nearly a century later. Records show other apartments are owned by the former U.S. Secretary of the Treasury Steven Mnuchin, fashion designer Vera Wang, and banking scion Jacob Safra.

The timing also intersects with renewed debate over New York’s proposed pied-à-terre tax, backed by Governor Kathy Hochul and Mayor Zohran Mamdani. The measure would apply to second homes valued at $5 million or more that are not used as primary residences. Griffin, now based in Florida, has been a central figure in that conversation since his record-setting Manhattan purchase helped revive earlier versions of the tax. For now, the possibility of added costs does not appear to be slowing him down.