Currency risk in international investing

Buy an international index fund and you've actually made two bets, not one: a bet on foreign companies, and a bet on foreign currencies against the dollar. Most investors never notice the second bet until a year when European stocks rise 10% in euros and their fund statement shows 2% — because the euro fell 8% against the dollar on the way.

How the mechanics work

Your unhedged international fund owns stocks priced in euros, yen, pounds, and dozens of other currencies. Its dollar value is (local stock return) × (currency move). When the dollar weakens, foreign holdings are worth MORE dollars — currency becomes a tailwind. When the dollar strengthens, it's a headwind. Through the 2010s and early 2020s, a persistently strong dollar shaved roughly 1–3% per year off US investors' international returns — a big part of why international 'underperformed' in that stretch.

Should you hedge it away?

Currency-hedged funds exist — they use forward contracts to strip out currency moves, delivering approximately the local return. The case for hedging: less volatility in dollar terms, and you're paid or charged a carry depending on interest-rate differences. The case against: over long horizons, currency moves have tended to wash out toward zero net effect, hedging adds costs and complexity, and unhedged foreign currency is itself a diversifier — it often pays off exactly when the dollar (and often the US market) is having a bad decade.

• For stocks held 10+ years: most evidence and most target-date funds favor UNhedged. Currency noise fades over decades, and the diversification when the dollar weakens is valuable.
• For foreign BONDS: hedge. Currency swings are several times larger than bond returns, so unhedged foreign bonds are mostly a currency bet with a small bond attached. Vanguard's international bond funds hedge for exactly this reason.
• For money you'll spend in dollars within ~5 years: it shouldn't be in international stocks anyway — the currency question is moot.

What this means in practice

1. Hold your international stock allocation unhedged by default — that's what standard total international index funds are, so you're likely already doing this.
2. If you own international bond funds, confirm they're hedged (the major broad ones are).
3. Don't chase last year's currency story. Hedged funds outperform in strong-dollar years, unhedged in weak-dollar years, and switching after the fact buys yesterday's weather.
4. Expect international returns to look 'wrong' versus local headlines sometimes — now you know the missing variable.

The bottom line

Currency is the invisible second engine on every international fund — sometimes a tailwind, sometimes a headwind, roughly a wash over long horizons. Leave stock exposure unhedged, keep bond exposure hedged, and treat dollar-strength cycles as noise to sit through rather than a signal to act on. The point of international investing is owning the world's companies; the currencies come along for the ride, and over decades the ride is usually fair.

A worked example: the same foreign return, three currency outcomes

Make the abstraction concrete. You put $10,000 into a European stock fund, and over the next year the underlying stocks gain exactly 10% in euros. If the euro-dollar exchange rate is unchanged, you earn 10% — $1,000. If the euro strengthens 8% against the dollar, your return stacks to roughly 18.8% — $1,880 — because each euro of stock value now buys more dollars. If instead the dollar strengthens 8%, your return shrinks to about 1.2% — $120 — the currency ate nearly the entire equity gain. Every unhedged international fund quietly runs this second engine alongside the stocks, and in any single year it can dominate: 2022's strong dollar turned decent local-currency foreign returns into ugly dollar ones, while 2017 and 2025 saw a weakening dollar hand US holders of international funds several free percentage points. Over multi-decade horizons the swings have largely canceled out — which is exactly why the standard advice is to ignore them rather than pay annually to remove them.

For completeness, hedged international funds do exist — they use forward contracts to strip the currency effect and deliver approximately the local-currency return. They cost slightly more, they add tracking complexity, and their hedging advantage flips sign every few years as the dollar cycles. Vanguard hedges its international bond funds (where currency swings would swamp the modest bond returns) but deliberately leaves its international stock funds unhedged (where the equity returns dominate and the currency exposure adds diversification) — a sensible split most investors can simply copy. The summary for a long-horizon stock investor: currency risk is real, visible in any single year, roughly self-canceling across decades, mildly diversifying against your all-dollar life, and not worth paying annual fees to remove.

Treat the currency line on your annual statement the way you treat any single year of stock returns: information about the weather, not the climate. The allocation decision was made for decades, and the exchange rate's contribution over that horizon has historically rounded toward zero.

In practical terms that means: buy the plain unhedged international stock fund, let your bond funds handle any hedging behind the scenes, and spend exactly zero minutes per year forecasting the dollar — a game that humbles professional currency desks and has no entry fee low enough for the rest of us.