When the privately owned auto parts manufacturer First Brands Group earlier this month began to be unable to service its $6.1 billion debt load, the financial press began to pick up on the story—not because it was so unique or important to the U.S. economy, but rather because various financial institutions, including the Swiss banking giant UBS Group AG, were admitting that their exposure to the company was higher and more complicated than they had previously shared, through their private credit funds.UBS’s ...