What is a currency overlay and when should an investor hedge foreign currency exposure?
For CFA Level III, I'm learning about currency management in multi-asset portfolios. The concept of a currency overlay seems separate from the underlying asset allocation. How does it work, what are the hedging strategies, and when is it optimal to hedge versus leaving currency exposure unhedged?
A currency overlay is a separate portfolio management layer that manages the foreign currency exposures arising from international asset holdings, independently from the underlying investment decisions.
Why Separate Currency Management?
When Granite Wealth Partners (hypothetical US investor) buys Japanese equities, it simultaneously takes on:
- Japanese equity market risk
- JPY/USD exchange rate risk
The portfolio manager selected those equities for their return potential — the currency exposure is incidental. A currency overlay allows a specialist to manage the FX risk independently.
Hedging Strategies:
| Strategy | Description | When Used |
|---|---|---|
| Passive (full) hedge | Hedge 100% of FX exposure using forwards | Minimize currency volatility; pure asset-return focus |
| Partial hedge | Hedge a fixed percentage (e.g., 50%) | Balance cost reduction with risk reduction |
| Active/discretionary | Vary hedge ratio based on FX views | Manager believes they can add alpha from FX |
| Cross-hedging | Hedge using a correlated but more liquid currency | When direct hedging is expensive (e.g., hedge BRL using MXN) |
| Macro hedging | Hedge the portfolio's aggregate FX sensitivity, not each position | Efficient for diversified multi-currency portfolios |
When to Hedge vs. Not Hedge:
Arguments for hedging:
- Currency contributes volatility but zero expected return in the long run (empirical finding)
- Short-term currency moves can overwhelm asset returns (e.g., 10% equity gain wiped out by 12% currency loss)
- Liability-driven investors need to match currency of liabilities
Arguments against hedging:
- Hedging costs money (forward points, bid-ask spreads)
- Some currencies provide natural portfolio diversification (e.g., JPY tends to appreciate in risk-off environments)
- Emerging market currencies are expensive or impossible to hedge efficiently
- Rolling forward contracts creates basis risk and operational complexity
Optimal Hedge Ratio Considerations:
The minimum-variance hedge ratio for currency i:
h* = (correlation between asset return and FX return) x (volatility of asset / volatility of FX)
But in practice, most institutional investors use a policy hedge ratio of 50-70% for developed market currencies and 0-30% for emerging market currencies.
Example — Granite's Overlay Decision:
- EUR/USD: Forward points favorable (positive carry for USD investor hedging EUR), correlation with EUR equities is 0.4 → hedge 70%
- JPY/USD: JPY provides diversification in risk-off scenarios → hedge 30%
- GBP/USD: Small allocation, hedging cost exceeds benefit → unhedged
For currency management practice, explore our CFA Level III question bank on AcadiFi.
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