What is the international Fisher effect and does it hold empirically?

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AcadiFi · Accepted Answer

The international Fisher effect (IFE) states that countries with higher nominal interest rates will see their currencies depreciate against countries with lower rates, with the depreciation rate equal to the interest differential. Formally: E[delta S] = i_domestic - i_foreign. The logic combines Fisher effect (nominal rates = real rates + inflation) with relative PPP.

Empirically, IFE performs poorly in the short and medium run. The 'forward premium puzzle' documents that high-yield currencies actually appreciate on average, generating the profitable carry trade. Over 1975-2020, a strategy of shorting low-yield and going long high-yield developed-market currencies earned 4-6% annualized excess return, directly contradicting IFE.

Why does IFE fail? Risk premia compensate carry-trade holders for crash risk. When risk-off episodes hit (2008, March 2020), carry trades unwind violently: AUD/JPY fell 30% in months. Over very long horizons (20+ years) and in hyperinflationary regimes, IFE does hold - very high nominal rates signal very high inflation and eventual currency collapse.

Ravenholm Currency Partners uses IFE as a theoretical benchmark but overlays risk-premium adjustments for tactical positioning. In practical terms, IFE is a textbook equilibrium that real markets deviate from for long periods.

What is the international Fisher effect and does it hold empirically?

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