Here's the story:
https://www.wsj.com/articles/united-...is-11586779535
This is the equivalent of a desperation bond issue, but on much foggier terms. The market value of a point / mile is liquid and pegged at the carrier's discretion, moment to moment. When you buy a bond you know what the maturity value and date will be. Buy a mile, and you have no idea of its value until you attempt redemption. Miles are a faithless currency, or ought to be. What a sad bed the airlines have made for themselves.