Sub-investment grade bond
From ACT Wiki
Credit ratings - bonds - securities
Sub-investment grade is a range of ratings attributed to a bond (or other security) that is assessed as being speculative (less certain in respect of the preservation of the capital invested) in the opinion of a credit rating agency such as Fitch Ratings, Moody’s or S&P (Standard and Poor’s).
Sub-investment grade represents credit ratings which are weaker than investment grade.
In Fitch and S&P's long term rating scales, sub-investment grade is BB and lower.
The equivalent in Moody's long term scale is Ba1 and lower.
Sub-investment grade is also known as 'non-investment' grade, 'speculative' grade, or sometimes 'spec' grade.