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28.08.2023
Bond Maths: How to Calculate Spread
Bond Maths: How to Calculate Spread
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Key thoughts

  • The bond spread is the difference in yield between the bond in question and its benchmark.

  • The benchmark bond is usually a government bond of the same country and similar maturity.

  • You need to see the spread to understand how your willingness to take the credit risk of the bond is being rewarded.

Spread is really a very easy to understand measure. It is the difference in yield between the bond you are looking at and some benchmark bond.

Usually the benchmark bond is the bond of the government that holds the currency in which the bond in question is denominated. The benchmark bond should also be fairly close in time to maturity to the bond being analysed.

Example:

The yield on the BNP bond on 1 August 2023 is 3.77% It matures on 20 May 2024. What is its spread?

The benchmark for this bond is the French government bond maturing in July 2024. Its yield is 3.6% on 1 August 2023. So the spread is 3.77% - 3.6% = 0.17%.

Spreads are usually expressed in basis points, which are percentage points multiplied by 100.

For the BNP bond in the example above, the spread in basis points would be 0.17% * 100 = 17 basis points. 

Why should you care about the spread?

Well, government bonds are usually considered to be the least risky investment. So when you invest in a bond issued by a private company or a bank that could theoretically go bankrupt, you want to know how much you are getting for the extra risk you are taking. This is where the spread comes into play.

Professional traders do not usually trade bonds in terms of price/yield, but rather in terms of the spread. If they see that the spread is disproportionate to the amount of risk being taken, they will buy or sell the bond with the aim of waiting for the spread to return to a fair level.

This article does not constitute investment advice or personal recommendation. Past performance is not a reliable indicator of future results. Bondfish does not recommend using the data and information provided as the only basis for making any investment decision. You should not make any investment decisions without first conducting your own research and considering your own financial situation.