the.com/fallen angel

means A bond that was originally issued with investment-grade credit quality but has since been downgraded to junk status, typically because the issuer's financial health deteriorated.

from The phrase borrows directly from the old religious image — an angel cast out of heaven, retaining the memory of grace but not the status. Financial writers and analysts picked it up sometime in the 20th century as credit-rating agencies formalized the investment-grade/junk divide, needing a term for bonds that fell from grace rather than being born speculative. It's a cousin, in spirit, to other market metaphors that borrow moral or cosmic imagery (think 'zombie companies' or 'black swan events') to make abstract credit mechanics feel vivid and human.