Why Brinson Attribution May Not Reconcile with Compounded Portfolio Returns

Summary

The document raises a reconciliation problem when applying the Brinson performance attribution model to year-to-date portfolio returns. The author reports that weighting fixed income, equity, and cash returns by their portfolio weights does not reproduce the portfolio’s compounded return. Using current weights with year-to-date returns also appears to make the attribution result collapse to a simple sum of component returns, rather than explaining the portfolio return through allocation and selection effects.

The concern points to the importance of compounding and rebalancing conventions in attribution: weights and returns need to be defined consistently over the measurement period, and a single snapshot of current weights may not represent the path of a portfolio. The document gives no data, calculation details, or proposed correction, so it identifies a potential implementation or methodology issue rather than demonstrating a general failure of Brinson attribution.

Key ideas

• Weighted component returns may not equal a portfolio’s compounded return.
• Attribution calculations depend on how weights and returns are measured over time.
• Using current weights with cumulative returns may fail to explain allocation and selection effects.
• The document identifies a reconciliation concern but provides no worked example or resolution.

Tags

# Problems with Performance Attribution Analysis


# Problems with Performance Attribution Analysis












I am using the typical Brinson Model formula, but it doesn´t work, I think that is explained because of the compound effect and rebalancing... when I look my portfolio's YTD return and multiply by the weight of each part (FI, Equity and Cash) the result of the sum of that three values is different from my compounding YTD. And when i calculate the Brinson Model for the Performance Attribution with the today's weights and YTD returns, the result is equal to the sum of each return (Fixed Income, Equity & cash) by the Total return.. Wrong thing, because in theory, the Brinson would give the my YTD return explained by a X and Y selection and allocation effect.

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