How Do Unexpected Changes in Interest Rates Explain the Variation of Excess Return: Testing an Extended Fama–French Five-Factor Model on the Swedish Stock Market

Abstract: In the realm of asset pricing models, the Fama-French five-factor model has become a foundational framework for explaining the variation of excess stock returns. However, as financial markets continue to evolve, there arises a need to explore potential extensions to capture additional sources of risk and return. One such extension involves incorporating the difference between the actual and expected interest rates as an additional factor. This report delves into the empirical testing of this extended model and assesses its implications for explaining the variation of excess returns on the Swedish stock market. The rationale behind introducing such a factor is rooted in its potential to capture variations in excess returns attributed to unexpected changes in interest rates. To evaluate its efficacy, a comprehensive analysis was undertaken, focusing on three key aspects: the statistical significance of the factor, its impact on model fit, and its role in explaining variations in excess returns. Upon conducting time-series regressions across three sets of nine portfolios, it was found that while the factor exhibited notable coefficients with substantial influence on explaining excess returns, it failed to achieve statistical significance. This outcome prompts a crucial question: can an extension with a factor of high explanatory power but low significance truly enhances our understanding of stock returns? The findings suggest that despite its influence, other factors present in the model might already absorb the explanatory potential attributed to the new factor. Further examination of the extended model's performance provides insights into the overall model fit. The GRS statistic indicates that the extended model offers a superior fit compared to the original five-factor model. However, the adjusted R2 values suggest that this enhanced fit is not translated into a meaningful improvement in the model's ability to explain variations in returns. This prompts a nuanced consideration of whether the complexity introduced by the additional factor aligns with its incremental ability to explain variation in returns.