Average Purchase Price (Cost Basis) changes when changing the reporting period

English
1

Hi everyone,

I’m using Portfolio Performance 0.86.1 on Windows.

I have a single Bitcoin position:

  • One buy transaction in 2021.
  • No additional buys.
  • No sells.
  • No transfers or deliveries.
  • The quantity has never changed.

What confuses me is that the Average Purchase Price (GAK / Cost Basis) changes when I change the reporting period in Performance → Securities Performance.

For example:

  • 3-year view
    • Cost Basis: €26,368.80
    • TWR: +109.94%
  • 1-year view
    • Cost Basis: €99,324.06
    • TWR: -44.26%

The number of Bitcoin, the current price and the portfolio value remain exactly the same. Only the Cost Basis changes.

My understanding is that the average purchase price should remain fixed because I have only one purchase transaction and have never sold any Bitcoin.

Is this expected behaviour? Does the “Cost Basis” column in the Securities Performance report represent something different when a reporting period is selected, or is this a bug?

Thanks in advance.

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2

As you realized the those KPI’s are reporting dependend.

Yes, otherwise you won’t have the possibility to work with individual reporting periods.

No!

3

Oke, thanks for your response.

I get it now.