Chicago knows what happens when Ken Griffin turns on a city, now Mamdani may find out

There is no clearer example of what happens when billionaire Ken Griffin turns on a city than Chicago, a blueprint now playing out in New York.

The Windy City, which served as Citadel's home for more than 30 years, has seen much of the firm's workforce shift south, with the office going from roughly 1,300 employees to a few hundred and still shrinking.

"Asking people to leave Chicago for New York or Miami has not been hard," Griffin said at a conference in New York on Oct. 6.

"Chicago, over the past six or seven years, has been engulfed in a series of problems," he said, pointing to crime as one of the city's most pressing challenges, along with broader economic and policy concerns weighing on employees' willingness to stay.

For Chicago, the result has been a steady erosion of one of its most prominent corporate anchors - shrinking office space, relocating employees and the departure of a billionaire who once poured hundreds of millions into the city's institutions and politics. It also meant fewer high-paying finance jobs downtown and the disappearance of a major civic and cultural benefactor.

That dynamic is now resurfacing in New York, where Griffin is locked in an escalating fight with Mamdani, echoing the early stages of his break with Chicago when Lori Lightfoot was mayor and JB Pritzker was governor of Illinois.

The dispute was sparked by Mamdani's viral April 15 video promoting a proposed tax on second homes worth more than $5 million. Filmed outside Griffin's 24,000-square-foot Central Park South penthouse - purchased for a record $238 million - the video singled out the hedge fund powerhouse by name.

"This is an annual fee on luxury properties worth more than $5 million, whose owners do not live full-time in the city. Like for this penthouse, which hedge fund CEO Ken Griffin bought for $238 million," Mamdani said in the clip.

Griffin has since criticized the video as "creepy and weird" during a discussion at the Milken Institute Global Conference on April 6. He said he watched it three times.

Asked about Citadel's plans for a $6 billion office tower at 350 Park Avenue, he said the firm is reassessing the project while doubling down on its expansion in Miami, which he called "unquestionably" the right choice.

The clash highlights a widening divide between progressive ambitions in major cities and the financial leaders who help drive their economies.

It also raises a broader question: whether New York could follow a path similar to Chicago's where a prolonged standoff between political leadership and one of its most powerful business figures ultimately ended in departure.

Meanwhile, Florida and other red states have branded themselves as business- and billionaire-friendly, welcoming high earners and balking taxes that would burden their empires.