Junk bond

In finance, a high yield bond (non-investment grade bond, speculative grade bond or junk bond) is a bond that is rated below investment grade at the time of purchase. These bonds have a higher risk of default or other adverse credit events, but typically pay higher yields than better quality bonds in order to make them attractive to investors.
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Noun
1. a (speculative) bond with a credit rating of BB or lower; issued for leveraged buyouts and other takeovers by companies with questionable credit
(synonym) high-yield bond
(hypernym) bond, bond certificate

A bond with a speculative credit rating of BB (S&P ) or Ba (Moody's) or lower is a junk or high yield bond. Such bonds offer investors higher yields than bonds of financially sound companies. Two agencies, Standard & Poors  and Moody's investor services, provide the rating systems for companies' credit.