Josh Kushner Richer Than Trump After Billionaires Back His Firm

A Kushner has built a multibillion-dollar fortune after some of the world’s most high-profile billionaires bought a stake in his investment firm.

It’s not the one you might think.

Josh Kushner, 37, has racked up a slew of successful venture investments since founding Thrive Capital in 2009. But his older brother Jared, who married Donald Trump’s daughter Ivanka and served as a senior adviser in his father-in-law’s administration, has long been the one in the spotlight.

That might be changing. Although Jared went on to found his own $3 billion investment-management firm, Affinity Partners, largely with Saudi Arabian funds, ...