Their specialists look into a company's situation and identify a bond score for the company. Every rating service has its own formula for measuring risk and its own sort of score scale. Generally, score scales are defined in letter grades, where an AAA score designates a safe, low-risk bond, and a D rating designates a high-risk bond.federal government bonds, are generally low-yield bonds. You can depend upon getting a payout however that payout will be little. which of these describes a bond personal finance. On the other side of the spectrum, you have what's not-so-affectionately referred to as, which are low-rated, high-risk bonds. In order to entice investors into purchasing these risky junk bonds, the releasing companies promise high yields.