There are several considering points to figure out the relative value of bonds. Most of fixed income investors are using similar way to value bonds both in the secondary market and primary market. The way to evaluate the relative value can also be referenced by the way how the credit rating companies are rating the issuers.
Above Figure shows a part of Standard & Poor’s Ratings Services’ corporate analytical methodology. (source: Corporate ratings methodology: Transparency. Comparability. Standard & Poor’s Ratings Services. (April 2004)) They classify the issuer as 1) country risk, 2) industry risk, and 3) competitive position as part of business risk profile, and 4) cash flow / leverage as financial risk profile, before adjusting these factors with their predefined modifiers.
Investors’ thought process is quite in line with the Standard & Poor’s framework. The best comparable will be the bonds issued by same issuer and being traded in the market, but not many companies issue the bonds with similar maturity with similar conditions. Hence, the investors should compare the bonds with other issuers’ bonds being traded in the market. To compare, the criteria to peers will include the issuers’ 1) country of risk, 2) industry risk and 3) credit ratings & outlooks. After defining the comparable issuer list based on the criteria, the investors will compare the bonds to the bonds with similar maturity, mostly as spread versus interest rate swap level.
For bond valuation, investors use spread versus interest rate swap level as the interest rate swap is matching the maturity with the bond. Comparing the yield level with benchmark U.S. Treasuries’ yield can be plausible as the maturity of benchmark U.S. Treasuries are frequently updated by new auctions, while the bonds issued are gradually maturing.