Billionaire Ken Griffin is fuming after Mayor Zohran Mamdani spotlighted his Manhattan penthouse in a viral video announcing a new pied-à-terre tax – and the hedge fund titan signaled he might even yank a $6 billion development project in the city.

In a video last week, Mamdani beamed as he stood in front of the Citadel founder’s 24,000-square-foot property at 220 Central Park South – which he scooped up for $238 million in 2019, the most expensive home sale in the country.

“We’ve secured a pied-à-terre tax,” the 34-year-old Democratic socialist rejoiced in the April 15 video.

“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.”

Griffin — whose net worth is estimated by Forbes at $50 billion — wasn’t amused. A top exec at his hedge fund sent a companywide email Thursday afternoon blasting the mayor’s comments – and hinting at a potential reversal on a massive Midtown project.

“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 mid-town New York,” wrote Chief Operating Officer Gerald Beeson in an email obtained by The Post.

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

Mamdani’s office did not immediately respond to The Post’s request for comment.

The Wall Street Journal earlier reported the email.

During his campaign, Mamdani promised voters free childcare, free buses and city-owned grocery stores, pledging to ramp up taxes on the rich to support the pricey proposals – though such a move is up to state lawmakers.

Governor Kathy Hochul – who is up for re-election this year – flipped on her initial resistance last week to support the mayor’s tax on luxury second homes in New York City, raising concerns around a possible wealth exodus.

Earlier this year, Hochul attempted to win back wealthy New Yorkers fleeing the state, saying it’s important to be “smart” about taxes, “not just taxing for the sake of taxing.”

“It is clear that Mayor Mamdani is not interested in that advice,” Beeson wrote in the email, after quoting the governor.

“It is shameful that he used Ken’s name as the example of those who supposedly aren’t carrying their fair share of the burdens associated with New York City’s often costly and wasteful spending,” the email continued.

“In doing so, the Mayor has once again manifested the ignorance and disdain of the elite political class towards those who have been consistently committed to building one of the greatest cities in the world.”

The email added that over the past five years, Citadel principals and team members – including non-NYC residents – have paid nearly $2.3 billion dollars in city and state taxes, and Griffin has contributed $650 million in charitable donations supporting New York City residents.

In 2022, Griffin announced he was moving Citadel headquarters from Chicago to Miami, Fla. – near his primary residence – after years of complaining about high taxes and rampant crime.

“I’ve lived in a failed city-state. I lived in Chicago for 30-some years. I had two colleagues who had bullets fly through their cars,” Griffin told Fox News’ Bret Baier in November 2025.

“I had 25 bullet holes in the front of my building where I lived. You can’t live in a city awash [with] violent crime,” he said.

Billionaire hedge fund manager Bill Ackman came to Griffin’s defense on social media, warning that such attacks from Mamdani could push more business to Florida.

“We should be applauding Ken for spending $238 million in NYC, not attacking him for doing so,” Ackman wrote in a post on X last week, arguing that non-resident owners of NYC properties drive economic growth without acting as a drain on local resources.

“Ken’s company is a major employer in NYC of very high paying jobs which drive a considerable amount of our tax base. We wouldn’t want him to move even more employees to Miami,” he continued.

CNBC anchor Sara Eisen hit out at Mamdani’s video shortly after it was released – seemingly forewarning that it could have consequences from Griffin.

She noted in a social media post that Griffin “employs thousands of people in NYC” and is “investing billions more and creating thousands more jobs” – adding that “making him feel unwelcome and demonizing him seems risky.”

“Meantime Miami is welcoming him and his firm, with the massive jobs, investment and tax revenue he’s bringing,” Eisen wrote.