Cboe Global Markets, parent company of the Chicago Board Options Exchange, is reportedly negotiating for space within Chicago’s Old Post Office. If completed, the deal would see the firm relocating from their current headquarters just across the river.

According to Crain’s, Cboe is seeking to lease approximately 175,000 square feet. The firm currently occupies most of 400 S. LaSalle Street—approximately 300,000 square feet—which the company developed in the 1980s and still owns.

New-York-based 601W Companies is in the midst of an $900 million renovation on the 2.8 million-square-foot, Art Deco building, located at 433 W Van Buren Street. The first tenants are scheduled to move in by September. Steve Smith, Jamey Dix and Daniel Heckman of The Telos Group are the brokerage team tasked with bringing tenants to the rejuvenated property. Chicago-based Bear Construction is acting as general contractor on the project, implementing a Gensler design.

Cboe would join scores of other companies rumored or confirmed to have taken space in the massive building. These include Cisco Systems, Uber, Walgreens, Ferrara Candy, the Chicago Metropolitan Agency for Planning, AbelsonTaylor, the Federal Home Loan Bank and Kroger subsidiaries Home Chef and 84.51°. If all of these deals close as reported, the Old Post Office would have approximately 1.4 million square feet locked up.