Wall Street's latest gold rush has found its new target: your retirement

Getty Images; Alyssa Powell/BI

What do an employee at a dental imaging company, an English Premier League soccer player, and a saver with an account at BlackRock all have in common? They're all quietly connected to Wall Street's hottest investment class: private credit.

The debt that most Americans have dealt with — from credit cards to mortgages — has been upfront: there are bills to pay, balances that are visible, and credit ratings that assess a borrower's creditworthiness. Private credit...