The fixed-income vehicles still represent a hedge against a global economic slowdown.
The gap between five- and 30-year rates grew to the widest in just over six weeks.
The inflation flare-up is taking a toll on demand, spending and corporate earnings.
He also remains bullish on gold, which advanced to the highest level in more than a year on Thursday.
The firms say buying the debt of companies on the cusp of an upgrade has the potential to unlock profits.