Charlie Mills, the chairman and former CEO of Northfield-based Medline Industries, was the buyer who paid $7.4 million last April for billionaire Ken Griffin’s unit on the 35th floor of the Gold Coast building at 9 W. Walton St. Mills and his wife now plan to spend another estimated $2.75 million to build out the space, according to a building permit filed with the city.

Griffin famously paid $58.75 million in 2017 for the top four floors in the building at 9 W. Walton, but he never built them out and left them as raw space. After declaring in 2022 his intention to move his company and his residence to Florida, Griffin took a major loss on the four floors, selling them for a total of $34.9 million, or a loss of more than 40%.

Griffin paid $12.5 million in 2017 for the 7,327-square-foot unit Mills purchased. Griffin first listed the 35th-floor unit in 2022 for $14 million. He took the condo off the market the following year, and then sold it for $7.4 million in April 2025 in an off-market deal to an opaque land trust that masks its beneficiary’s name.

But a December 2025 building permit on file with the city of Chicago lists Mills as the current owner of the full-floor unit and shows that he hired architect Michael Waechter and contractor Wujcik Construction to proceed with the initial buildout, which will have an estimated cost of $2.75 million for materials and labor.

In a brief interview with Elite Street, Mills called 9 W. Walton “a very, very nice building, and my wife and I hope to build a very nice home there.”

In buying a condo in the building at 9 W. Walton from Griffin, Mills joins Gov. JB Pritzker, who paid $19 million in 2024 to buy the top two floors of the building from Griffin. The buyer who paid $8.5 million in April for Griffin’s 36th-floor unit at 9 W. Walton remains a mystery.

Pritzker has not yet taken out a permit with the city to build out his top two floors at 9 W. Walton.

Medline underwent an initial public offering in December. Mills’ family previously had sold a majority stake in Medline to private equity firms in 2021.

Bob Goldsborough is a freelance reporter.