The airline sweetened the yield on a $2.25 billion junk-bond sale after investors expressed concerns about the fleet.
The perception of Fed backing helps risky firms borrow anew and emboldens investors to make risky bets.
New junk bonds and IPOs have observers worried that the market's trying to have a last hurrah at investors' expense.
The firm helped find drug kingpin El Chapo, but may have helped Saudi Arabia track political dissidents.