Serial Bonds: What They Are, How They Work, and Pros & Cons

A serial bond is a structured bond issue in which a portion of the bonds mature at regular intervals until all have reached maturity. This gradual maturation method is commonly used to finance projects that provide a steady income stream, facilitating bond repayment. All bonds within the issue are sold to the public simultaneously, and their respective maturity dates are outlined in the offering documents.

A serial bond structure serves to mitigate the risk of missing principal or interest payments and bond defaults. While a serial bond requires the issuer to repay specific bondholders on set dates, other bond issues opt for a sinking fund.
A serial bond structure is frequently used for municipal revenue bonds, typically financing projects that generate fees and income for states and cities. For instance, if a city builds a sports stadium funded by parking fees, stadium concessions, and lease income, a serial bond structure is fitting. If the issuer believes the facility can generate consistent annual income, they structure the bond with serial maturity dates. As the outstanding bond amount decreases, the risk of default on the bond issue also diminishes.

In a sinking fund, the issuer makes periodic payments to the bond issue’s trustee, who then purchases bonds in the open market and retires them. The trustee acts in the interest of bondholders, utilizing sinking fund payments to buy and retire bonds. Unlike retiring bonds on a specific schedule, the trustee buys bonds from any willing bondholder. Both sinking funds and serial bond issues effectively reduce the total dollar amount of outstanding bonds over time.

Municipal revenue bonds, such as those used to finance infrastructure or fee-generating facilities, often benefit from the structure of serial bonds. These projects generate income through various means, like toll collections, utility fees, or lease agreements. Serial bonds are a sensible choice for such revenue-backed initiatives because they ensure the repayment schedule aligns with the project’s income stream.

Bond rating agencies play a crucial role in assessing the creditworthiness of bond issues. Serial bonds typically fare well in these assessments because of their structured repayment schedules. A bond with serial maturities is seen as having more creditworthiness compared to a bond with a single maturity date. If a serial bond experiences issues and misses interest payments many years after the initial issuance, a certain portion of the bonds has already been paid off, reducing the overall risk to investors.

Serial bonds align the project’s income stream with the bond repayment schedule, reducing the risk of default and making them a preferred choice for fee-generating projects.

In a sinking fund, periodic payments are made to buy and retire bonds on the open market. In contrast, serial bonds rely on staggered maturation, reducing the total outstanding bond amount over time.

Bond rating agencies typically view bonds with serial maturities as more creditworthy due to their structured repayment schedules. If a serial bond faces issues, the reduced outstanding bond amount enhances the issuer’s chances of financial recovery.

Serial bonds may not be the best choice for projects with irregular or unpredictable income streams. They work best when the project generates consistent revenue over time.

One challenge lies in managing various maturation dates, as this can be complex. Additionally, issuing serial bonds may involve higher administrative costs compared to other bond structures.