Macaulay duration calculation

Macaulay duration of a financial asset is the weighted average maturity of cash flows, and it is given by:

$MacD = \frac{\displaystyle \sum_{i=1}^{n}{t_i PV_i}} {\displaystyle \sum_{i=1}^{n}{PV_i}} = \frac{\displaystyle \sum_{i=1}^{n}{t_i \frac {CF_i}{(1+y)^i}}} {\displaystyle \sum_{i=1}^{n}{ \frac {CF_i}{(1+y)^i}}}$

where:

• $i$ indexes the cash flows
• $t_i$ is the time in years until the $i^{th}$ payment will be received
• $PV_i$ is the present value of the $i^{th}$ cash payment from the asset
• $CF_i$ is the $i^{th}$ cash payment from the asset
• $y$ is the yield to maturity

Using the following spreadsheet the Macaulay duration of the S100 bond is $\boxed{4.24}$ .