Why does uncovered interest parity fail empirically?

The Uncovered Interest Parity theory, predicated on perfect capital mobility and a floating exchange rate regime, faces challenges in real-world contexts marked by capital restrictions and diverse exchange rate regimes. This research investigates the validity of the UIP hypothesis in selected OECD countries, considering the role of capital control and de facto exchange rate regimes. By analyzing annual and monthly data, including immediate rates, short-term borrowing rates, and 10-year government bond rate differentials, several panel estimation techniques and alternative empirical models are employed. The results are robust to sub-sample analyses, alternative specifications of the empirical model, and different estimation methods. The study provides evidence supporting the UIP, particularly for immediate and short-term interest rates. The empirical examination underscores the necessity of accounting for the de facto floating exchange rate regime and capital flow restrictions when testing the UIP model. Consequently, the UIP hypothesis moves beyond being a theoretical fallacy and emerges as empirically verifiable, holding significant implications for policymakers and advancing the understanding of international finance.