Citadel has officially inked a deal for a huge office at 660 Fifth Ave., signing the largest new office lease over the last three months of 2024.

Ken Griffin’s hedge fund is taking over 500K SF in Brookfield Properties’ trophy building, according to reports by Savills and Colliers.

The lease was the second-largest in Manhattan during the fourth quarter, behind Bloomberg’s 925K SF renewal and expansion at 919 Third Ave. The deal is significantly larger than previous reports by Business Insider that Citadel was looking to take 365K SF in the 39-story Midtown tower.

Spanning 1.4M SF, 660 Fifth Ave. was renovated in 2022, offering a new lobby and 42K SF of exclusive tenant terraces on four of its levels, per the developer’s website. Brookfield spent $400M renovating the building after taking it over from Kushner Cos. in a $1.1B ground lease deal.

Citadel will occupy 20 floors of the 39-story tower, on the corner of 52nd Street, according to a Brookfield spokesperson.

“We are proud to welcome Citadel to their new office at 660 Fifth Avenue,” Callie Haines, Brookfield's executive vice president and head of Northeast Region office properties, said in a statement. “This landmark lease underscores the success of our extensive redevelopment of 660 Fifth Avenue, transforming it into a premier, cutting-edge, and sustainable workplace in the heart of Midtown Manhattan.”

A spokesperson for Citadel didn't immediately respond to a request for comment.

Citadel employees are moving into the space while a joint venture of Griffin, Vornado Realty Trust and Rudin is building a supertall at 350 Park Ave. where Citadel has agreed to occupy approximately 850K SF of the nearly 2M SF tower, according to public filings. The company also anchors 425 Park Ave. with a 440K SF lease.

Griffin has been an advocate for return to work, previously speculating that unemployment will rise as bosses aren’t able to make in-person connections with employees. After his firm made $16B in 2022, becoming the world’s best-performing hedge fund, he credited that success to strict office mandates.

Last year, Citadel also expanded its office presence in Miami. At the recently opened tower at 830 Brickell, Citadel signed on for 130K SF across eight floors as of June.

The firm announced it would relocate its headquarters from Chicago to Miami in June 2022. In the company's adopted hometown, Griffin is developing a supertall with 1.3M SF of office space and 212 hotel rooms, according to plans filed in August. Griffin said last month that the building, for which he is leading the development, would be a global icon, Bisnow reported.

Citadel’s Fifth Avenue lease, alongside deals by JPMorgan Chase at 277 Park Ave. and Blue Owl Capital at 375 Park Ave. added to the continuing domination by finance, insurance and real estate firms of the office market, combining for 44% of all fourth-quarter leasing activity, according to Colliers.

UPDATE, JAN. 2, 2:25 P.M. ET: This story has been updated with a statement from Brookfield.