Currency Risk in Practice: Worked Example and Portfolio Context

The Setup: A US Investor in Japanese Equities (2012 to 2023)

The Japan equity market from 2012 through 2023 provides one of the clearest real-world demonstrations of currency risk in action. During this period, Japanese equities surged in yen terms, driven by Abenomics (the economic stimulus program launched by Prime Minister Abe in late 2012), corporate governance reforms, and a globally accommodative monetary environment. At the same time, the Bank of Japan maintained ultra-loose monetary policy while the US Federal Reserve raised rates sharply from 2022 onward, causing dramatic yen depreciation.

The combination produced a striking divergence between what a Japanese investor and a US investor experienced from the same underlying equity positions. The Nikkei 225 index rose from approximately 8,455 at the end of 2011 to approximately 33,464 at the end of 2023, a gain of roughly 296% in yen terms over 12 years. Meanwhile, the exchange rate moved from approximately 76 yen per dollar at the end of 2011 to approximately 141 yen per dollar at the end of 2023, representing a yen depreciation of approximately 46% against the dollar.

This worked example uses these approximate figures to illustrate the mechanics. Precise numbers will differ depending on exact dates and the index used, but the dynamics are representative of the actual investor experience during this period.

The Unhedged Return: Step-by-Step Calculation

Consider a US investor who placed $10,000 into a fund tracking the Nikkei 225 (or Japanese equities broadly) at the end of 2011 and held through the end of 2023 with no currency hedge.

Step 1: Convert dollars to yen at entry. At 76 yen per dollar, $10,000 converts to 760,000 yen.

Step 2: Apply the equity return in yen terms. The Nikkei 225 rose from approximately 8,455 to 33,464, a factor of 3.958. The 760,000 yen investment grows to 760,000 times 3.958, equaling approximately 3,008,080 yen.

Step 3: Convert yen back to dollars at exit. At 141 yen per dollar, 3,008,080 yen converts to approximately $21,333.

Step 4: Calculate the dollar return. ($21,333 minus $10,000) divided by $10,000 equals 113.3% total return over 12 years, or approximately 6.4% annualized.

In yen terms, the same investment returned 295.8% total, or approximately 12.6% annualized. The difference (6.2 percentage points per year) is entirely attributable to yen depreciation against the dollar. The investor captured roughly half the equity return in dollar terms.

The Hedged Return: Adjusting for Forward Carry

A hedged investor used a rolling currency forward to lock in the forward exchange rate each month (or quarter), neutralizing yen movements. Their return in dollar terms closely tracks the yen-denominated equity return, adjusted for the cumulative cost (or gain) of the forward carry over the period.

The cost of hedging yen back to dollars depends on the interest rate differential between the US and Japan. From 2012 through 2021, US rates were also near zero, so the forward cost was minimal (less than 0.5% per year). From 2022 through 2023, US rates rose sharply to 4% and above while Japan held near zero, pushing the hedging cost to 4% to 5% per year during that specific window.

For a rough approximation across the full 2012 to 2023 period, assume an average hedging cost of approximately 1% per year. Cumulative over 12 years, that roughly 12% cumulative cost (applied to the investment amount, compounding) would reduce the hedged investor's total return to approximately 295.8% minus roughly 11 to 13 percentage points of cumulative drag, leaving an approximate hedged total return of around 283% (again in rough terms, as compounding makes the precise calculation more complex).

The hedged investor earned approximately 283% versus the unhedged investor's 113% over 12 years, a difference of roughly 170 percentage points of cumulative return, because the hedged investor retained the yen equity gain while the unhedged investor had that gain substantially eroded by the depreciating yen.

Important note: This outcome is not a universal argument for always hedging. The unhedged investor still earned 113% (6.4% annualized) over 12 years, which is a reasonable outcome for an international allocation. The comparison works out strongly in favor of hedging in this specific case because the yen depreciated severely and hedging was cheap in the early years. In a period where the foreign currency appreciated against the dollar, the unhedged investor would outperform the hedged investor by the sum of the currency gain and the hedging cost saved.

Visualizing the Return Components

Note on the exchange rate effect calculation: when the yen depreciates from 76 to 141 yen per dollar, the dollar has strengthened by 85% against the yen (141 divided by 76, minus 1). From the yen investor's perspective, the yen has depreciated by 46% against the dollar (1 minus 76 divided by 141). These are two different ways of expressing the same rate change; for calculating a dollar return on a yen-denominated asset, you divide the ending yen value by the ending exchange rate (yen per dollar), which automatically incorporates the depreciation effect.

How Currency Volatility Affects Portfolio Sizing

Understanding the currency impact on returns is useful for planning. When currency risk adds substantially to total portfolio volatility, it should be considered when deciding how large the international allocation should be.

A practical approach is to estimate the total annualized volatility of a proposed international position, including the currency component. For unhedged developed-market equities (such as broad European or Japanese equity funds), the total dollar return volatility is typically 15% to 20% per year, compared to 13% to 16% for a US equity fund with no currency overlay. The currency component adds roughly 6 to 8 percentage points of annualized standard deviation on top of the local equity volatility, though the correlation between the two is not always 1.0, so the combined volatility is less than the simple sum.

For emerging market equity funds, the combined volatility is typically 20% to 28% annualized, compared to 16% to 22% for the local equity index alone, because EM currencies are more volatile and tend to move in the same direction as EM equity markets during risk-off periods.

A common portfolio construction guideline is to size the international allocation so that currency-driven volatility does not dominate total portfolio risk. If your portfolio's target total volatility is 12% and you want no single factor to contribute more than 2% of that, you would want to keep unhedged international exposure below a level where currency volatility (say 7% annualized on a 30% allocation in a major pair) contributes more than 2% at the portfolio level (which would imply roughly 0.30 times 0.07 equals 2.1% portfolio-level currency volatility, just at the threshold).

This is a guideline, not a rigid formula. Many investors hold 20% to 40% of their equity allocation in international markets without hedging and find the total volatility manageable over long holding periods. The key is to make the decision deliberately rather than by default.

Lessons from the Japan Example for General Portfolio Management

The Japan 2012 to 2023 case illustrates several principles that generalize beyond this specific market.

First, currency effects can be large relative to equity returns over multi-year periods, not just short-term noise. A 46% currency depreciation materially reduced a strong equity outcome. Second, the direction of the currency effect is not predictable in advance. Investors buying Japan in 2012 could not know the yen would depreciate as severely as it did; some forecasters expected the opposite. Third, the cost of hedging varies enormously over time depending on rate differentials. A strategy that was nearly free to implement in 2013 became expensive by 2023, which argues for revisiting hedging posture as rate environments change rather than setting it once and forgetting it.

Fourth, even the unhedged investor earned a reasonable absolute return. Japan at 6.4% annualized over 12 years is not a bad outcome, which is a reminder that currency risk is a source of volatility and uncertainty, not a guarantee of loss. Finally, the currency-hedged outcome was substantially better in this specific case, but that was a contingent result of yen weakness. Had the yen strengthened instead of weakening, the hedged investor would have sacrificed that gain at the cost of the forward carry.

For investors building a long-term globally diversified portfolio, the Japan example is a useful calibration tool rather than a reason to always hedge or never hedge. It makes the stakes concrete and gives realistic numbers to the tradeoffs described in a framework discussion.