Citadel double down as Ken Griffin expands Miami footprint amid Mamdani feud

Billionaire hedge fund CEO and owner Ken Griffin is making good on his promise to “double down” on Miami after publicly feuding with New York City Mayor Zohran Mamdani over New York’s new tax on expensive second homes.

Griffin, who runs hedge fund Citadel, plans to add a 300-unit apartment building and a 1,400+ space parking garage to the site of Citadel’s future headquarters in Miami’s financial district Brickell, recent filings show.

Citadel also acquired every unit in a 22-story condominium tower across the street from the Brickell building with plans to demolish it to expand the Miami campus.

“We are focusing this part of our development at 1201 Brickell solely on commercial office space. Miami is open for business, and the unparalleled quality of our development will drive the tenancy of leading global firms, including Citadel and Citadel Securities,” a Citadel spokesperson told FOX Business.

On April 15 (Tax Day), NYC Mayor Zohran Mamdani posted a video outside Ken Griffin’s Manhattan penthouse promoting a new “tax-the-rich” policy. (Spencer Platt/Aaron Schwartz/Bloomberg/Getty Images / Getty Images)

The Miami push follows a protracted feud between Griffin and Mamdani, stemming from a video Mamdani made specifically targeting Griffin’s Park Avenue penthouse in an explainer for his new city tax on expensive second homes. 

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“When I ran for mayor, I said I was going to tax the rich. Well, today we’re taxing the rich… This is an annual fee on luxury properties worth more than $5 million whose owners do not live full-time in the city — like this penthouse, which hedge fund CEO Ken Griffin bought for $238 million,” Mamdani said in his April 15 video while standing in front of Griffin’s penthouse. 

New York City Mayor Zohran Mamdani stands outside of Citadel CEO Ken Griffin’s Park Avenue penthouse in an April 15, 2026, video. (NYC Mayor’s Office / Unknown)

Griffin responded, calling the personal attack “creepy and weird,” worrying that it put him in harm’s way and demonstrated “a profound lack of judgment,” on Mamdani’s part. 

Griffin’s Citadel executives then suggested that a new Citadel office space in Midtown could become a casualty of Mamdani’s not-so-business-friendly policies.

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“We are about to commence the redevelopment of 350 Park Avenue, creating 6,000 highly paid construction jobs and supporting the creation of more than 15,000 permanent jobs in Midtown New York,” Citadel COO Gerald Beeson wrote in an April 23 memo to employees. 

Citadel is building its future headquarters in Miami’s financial district Brickell. (Getty Images / Getty Images)

“The project – if we move forward – will entail more than $6 billion dollars of spending,” he also wrote.

Mamdani eventually softened his rhetoric, thanking Griffin for his contributions to the city.

Citadel already moved its headquarters from Chicago to Miami in 2022, and the Brickell acquisitions further grow the hedge fund’s South Florida footprint.

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FOX Business contacted Mayor Mamdani’s office for additional comment. 

FOX Business’ Madison Alworth and Matthew Kazin contributed to this report.