Chicago Family Worth $26 Billion Is Building an Investment Firm

The Mills family, which ascended to the ranks of the world’s wealthiest dynasties after selling Medline Industries last year, is building its own investment firm to deploy its vast fortune.

Medline President Andy Mills, a fourth-generation member of the Chicago-based family, has formed Council Ring Capital and assembled a team to help manage a portion of its wealth, according to a person with knowledge of the matter. Council Ring has about $5 billion in assets, said the person, who asked not to be identified because the information is private.

Chief Investment Officer Chuck Murphy, a former executive at Longview ...