Investment-grade bond

Anyone who buys a bond is thereby lending money to a government or a company. In return, they receive regular interest payments and, at the end of the term, get back the amount they lent. This only works, however, if the borrower remains solvent. Specialized rating agencies therefore assess how likely it is that repayment will be made on time, and assign letter grades for this. If the grade falls in the upper range of this scale, it is called an investment-grade bond. The term thus does not mean that the investment is guaranteed to be safe, but that a default is considered unlikely.

The invisible line in the bond market

The dividing line between investment grade and the range below it is not a mere formality. A great many large investors are only permitted to buy above this line. Pension funds, insurers, and many funds have enshrined this in their own rules or by law. This means that a single letter grade determines how large the pool of potential buyers can even be.

For the borrower, this has direct consequences for its costs. A company with a good rating might pay three percent interest per year, while one with a worse rating pays eight percent or more. For a bond worth one billion euros, that quickly amounts to a difference of fifty million euros per year. This is why chief financial officers fight hard to maintain their rating.

If a company slips below the line, this is referred to in industry jargon as a fallen angel. Funds must then partially sell off the securities, even though nothing has actually changed about the business itself in the short term. As a result, the price often falls more sharply than the news alone would justify.

How the letter grades come about

The ratings come from a small number of large agencies, above all S&P, Moody’s, and Fitch. Their scales start at AAA, the best grade, and range through AA, A, and BBB down to C or D. Investment grade covers everything from AAA down to and including BBB-. Everything below that is officially called non-investment-grade, and in everyday language is usually referred to as junk bonds or high-yield bonds.

To determine the rating, analysts examine the borrower’s figures closely. What matters most is debt in relation to earnings, available cash, and the stability of the business. For governments, tax revenues, economic growth, and political reliability also count. This analysis results in a judgment, not a calculated outcome.

A common misconception is that the rating says something about the price trend. It only estimates the probability that interest payments and repayment will fail to materialize. An AAA bond can still fall in value, for instance if general interest rates rise. And the agencies do make mistakes: before the 2008 financial crisis, many securities that later became worthless carried top ratings.

Where the rating shows up in portfolios and in the news

Anyone investing in bonds through a fund or an ETF savings plan encounters this distinction immediately. Products carry names like Euro Corporate Bond Investment Grade and buy exclusively above the threshold. Alongside these, there are high-yield funds that deliberately collect lower-rated securities, offering higher interest in exchange for higher risk. Many life insurance policies and occupational pensions also hold predominantly investment-grade assets.

In financial news, coverage mostly concerns movements around this threshold. Headlines like Agency lowers outlook for France to negative or Automaker loses investment-grade status are typical. Such news moves prices because it changes the financing costs for entire countries or corporations.

Technology companies also play a role here. Building data centers for artificial intelligence costs tens of billions and is often financed through bonds. Companies like Microsoft or Alphabet receive top ratings for this and thus very favorable interest rates. Smaller AI providers without such ratings have to pay significantly more, which noticeably slows their expansion.