Family Offices Flock to $140 Billion Market for Secondary Sales

Chicago’s Mills dynasty built one of the world’s biggest health-care fortunes over the past century, but these days they’re part of a group driving another multibillion-dollar market.

The family office for the clan behind Medline Industries led a recent spin-out deal for biotech company Medix Biochemica from a European private equity fund, joining scores of investment firms for the mega-rich betting on the so-called secondaries sector.

Charles Mills, founder of Council Ring Capital

Photographer: Patrick Semansky/AP Photo

Family offices’ allocations to secondaries — where backers of closely held companies sell stakes to others — have surged as buyout firms and other investors grapple with pinched liquidity amid higher borrowing costs. ...