By Joy Wiltermuth and Isabel Wang

'It's fair to say that at some point - at some time - there will be a crisis,' says billionaire John Arnold, a former star Enron trader and the founder of philanthropy Arnold Ventures

The Treasury Department's efforts to calm the bond-market selloff haven't yet worked as well as hoped.

You can't just sweep $40 trillion in U.S. national debt under a rug and forget about it.

That's the bond market's message to Treasury Secretary Scott Bessent in recent days, following his sudden efforts to calm an alarming selloff in long-term U.S. government bonds that recently pushed yields up a two-decade high.