The core idea
A fallen angel is a bond that was issued with an investment-grade rating but was later downgraded into high yield.
What is happening underneath
The transition can create forced selling from investment-grade mandates while attracting specialist high-yield investors.
How investors should read it
This change in investor base can produce unusual relative-value opportunities and liquidity pressure.
The same market move can carry different information depending on which maturity, issuer and risk premium is changing. Read the question together with the underlying concepts rather than treating one price move as a universal signal.