Publicis Groupe has put 350,000 square feet of its downtown Chicago offices up for sublease.

The media holding company formally hit the market this week with its 14-floor listing at 35 W. Wacker Drive, according to a marketing flyer from brokerage Cushman & Wakefield. The offering becomes the city's largest block of available office space on the secondary market, shattering the mark previously held by Groupon's nearly 291,000-square-foot sublease listing at 600 W. Chicago Ave.

Publicis—whose brands include Leo Burnett Worldwide, Digitas and several other advertising, marketing and market research firms located with the building—said in a statement that the sublease listing “is a normal course of business aligned with our future of work planning, rooted in purposeful time together in the office, with flexible models that benefit both talent and our business.”

Last week Publicis that its net revenue rose by 20% year over year in 2022, its second consecutive year of double-digit growth.

Publicis occupies 32 floors in the tower, long known as the Leo Burnett Building, and is offering a mix of different floors for sublease, according to the Cushman flyer. The company's lease runs through the end of 2030. 

The Publicis sublease listing is also a troubling move for Opal Holdings, the New York-based real estate investment firm that paid $415 million in late 2021 for the tower at 35 W. Wacker. While Publicis still has almost eight years left on its lease, its move to cut back on space signals how much smaller its footprint may be in the future. The offering also comes as the building's second-largest tenant, law firm Winston & Strawn, is likely to leave the building when its lease expires and is eyeing a new office at 300 N. LaSalle St. Publicis and Winston today lease more than three-quarters of the 1.1 million-square-foot Wacker Drive tower.

An Opal Holdings spokesman did not respond to a request for comment.

The Cushman flyer plays up a variety of 25,000-square-foot floorplans in Publicis' space and notes that plans are in the works for a new lobby and tenant lounge in the building. Some of the floors were updated as recently as 2018, when Publicis relocated some of its brands into the building from the Merchandise Mart.