This Treasury Official Is Running the Bailout. It’s Been Great for His Family.

Federal Reserve Chairman Jerome Powell and Treasury Secretary Steven Mnuchin have become the public faces of the $3 trillion federal coronavirus bailout. Behind the scenes, however, the Treasury’s responsibilities have fallen largely to the 42-year-old deputy secretary, Justin Muzinich.

A major beneficiary of that bailout so far: Muzinich & Co., the asset manager founded by his father where Justin served as president before joining the administration. He reported owning a stake worth at least $60 million when he entered government in 2017.

Today, Muzinich retains financial ties to the firm...