Currency Risk in a Global Portfolio: Should You Hedge?

A UK investor buys a global equity fund, watches world markets rise 8% over a year, and opens their account to find they are up 3%. Nothing went wrong with the investments. The pound simply strengthened, and part of the return evaporated on the way home. This is currency risk, and for anyone holding overseas assets it is a permanent, unavoidable second engine driving your returns. This guide explains where the exposure comes from, how large it really is, what currency hedging does and costs, and how to decide whether you need it.

Key Takeaways

Question	Short, Practical Answer
Where does currency risk come from?	Any asset priced in a currency other than the one you spend, whatever exchange you bought it on.
How big is the effect?	Major currency pairs commonly move 8% to 12% a year, which can swamp a year of equity returns.
Does hedging reduce risk?	For bonds, substantially. For global equities, far less than most people expect.
What does hedging cost?	A slightly higher fund charge plus a rolling cost driven by the interest rate gap between the two currencies.
Common rule of thumb?	Hedge your bonds, leave your global equities unhedged, and revisit only if your time horizon is short.
Hidden cost to watch	Your broker’s FX conversion spread on every trade and every dividend, which is often the larger drag.

1. What Currency Risk Actually Is

Every investment you own has two returns stacked on top of each other. The first is what the asset did in its own currency. The second is what that currency did against yours. Your actual result is the two multiplied together.

Suppose you hold a US stock that rises 10% in dollars over a year. If the pound also strengthens 10% against the dollar in the same period, your sterling return is roughly zero. If instead the pound weakened 10%, your sterling return is closer to 21%. The company performed identically in all three cases.

The formula is simple enough to keep in your head: your return is approximately the asset return plus the currency move, plus a small interaction term that only matters when both are large.

You do not spend dollars, yen or euros. Whatever your holdings are priced in, your return is only real once it is measured in the currency you buy groceries with.

2. The Mistake Almost Everyone Makes About Listing Currency

This is the single most common misunderstanding in the whole topic, so it is worth stating clearly.

The currency a fund is priced in is not the currency risk you are taking.

If you buy a London-listed, sterling-denominated ETF that tracks the S&P 500, you have not avoided dollar exposure. The fund holds American companies whose shares trade in dollars. The sterling price on your screen is just a translation of the dollar value, updated continuously. When the dollar moves, that sterling price moves with it.

What determines your currency exposure is what the fund owns, not what ticker line it trades on. A sterling-priced global equity fund gives you exposure to every currency in that index, weighted by its holdings. The only thing that genuinely changes your exposure is an explicit hedge, which will be spelled out in the fund name, usually as “GBP Hedged” or a suffix like GBPH.

Where your real exposure sits

For a typical global equity index fund, the currency breakdown is dominated by the dollar, often 60% to 70% of the fund, with the rest spread across the euro, yen, sterling and a long tail of others. A UK investor holding a global tracker inside an ISA has, whether they realise it or not, made a very large bet on the dollar.

3. How Big Is the Effect, Really?

Currency moves are not a rounding error. Major pairs such as GBP/USD have routinely moved 8% to 12% within a year, and considerably more in stressed periods. Compare that to a long-run equity return in the high single digits and the scale of the issue becomes obvious.

Over a single year, currency can be the dominant factor in your return. Over a decade or more, the effect tends to wash out somewhat, because exchange rates between developed economies are broadly mean-reverting rather than trending indefinitely. That difference in time horizon is the entire basis for the hedging decision.

The one place currency genuinely helps

Sterling has a long-observed tendency to weaken during global risk-off episodes, while the dollar tends to strengthen. For a UK investor holding unhedged overseas equities, that means the currency effect frequently cushions a crash: your foreign holdings fall in their own currency, but each unit of that currency is now worth more pounds. It does not always work, but it is a genuine and underappreciated benefit of leaving equities unhedged.

4. What Hedging Actually Does

A currency-hedged fund uses short-dated forward contracts to neutralise the exchange rate effect, typically rolled monthly. The intent is that you receive the local-currency return of the underlying assets and little else.

What it costs

• A higher ongoing charge. Hedged share classes usually carry a modestly higher fee than their unhedged twin.
• The interest rate differential. This is the big one. The cost or benefit of a hedge is driven by the gap between short-term interest rates in the two currencies. If your currency has lower rates than the one you are hedging, the hedge has an ongoing cost. If higher, it can actually pay you.
• Tracking imperfection. Hedges are rebalanced periodically, so between rebalances the hedge and the underlying value drift apart. In volatile months this residual is visible.

What it does not do

Hedging does not reduce the risk of the underlying assets. A hedged global equity fund still falls when global equities fall. It removes one source of variation and leaves the larger one entirely intact.

5. Bonds Versus Equities: Why the Answer Differs

Here is the part that resolves most of the confusion. The right hedging decision depends on how big the currency movement is relative to the asset’s own volatility.

Overseas bonds: hedge them

A global government bond fund might have annualised volatility around 4% to 6%. Currency movements of 8% to 12% completely dominate that. An unhedged overseas bond holding is, in practice, a currency bet wearing a bond costume, and it fails at the job most people buy bonds for, which is being the stable part of the portfolio. The strong consensus, and the reason most global bond funds sold to UK investors are hedged by default, is that overseas bond exposure should be hedged to your home currency.

Global equities: usually leave them alone

Global equities carry volatility of roughly 15% or more on their own. Adding currency volatility of around 8% does not produce 23% total, because the two are not perfectly correlated and, as noted above, currency often moves the helpful way in a crisis. The reduction in total portfolio volatility from hedging equities is real but modest, and it comes at a permanent cost and with a lost crisis cushion. Most long-horizon investors reasonably conclude it is not worth it.

Hedge the asset class where currency is the loudest voice in the room. For bonds that is currency. For equities it is the equities.

6. When Hedging Does Make Sense for Equities

The general rule has genuine exceptions. Consider hedging equity exposure if:

• Your horizon is short. If you need the money within three to five years, you do not have time for currency effects to average out.
• You are drawing an income. A retiree spending in pounds is exposed to currency on every withdrawal, and a bad exchange rate at the wrong time compounds sequence-of-returns risk.
• You hold a single-country fund. Concentrated exposure to one overseas market means one undiversified currency bet, rather than a spread of them.
• The volatility genuinely stops you sleeping. A hedged fund you hold through a rough patch beats an unhedged one you sell.

A common middle path is to hedge part of your overseas equity exposure, perhaps half, so that no single currency outcome dominates your feelings about the portfolio. It is not optimal by any formula, but it is a defensible way to avoid the worst behavioural outcomes.

7. The Cost Almost Nobody Counts: Broker FX Fees

While investors debate hedged versus unhedged share classes, a larger and more certain cost frequently goes unnoticed: the exchange rate spread your broker applies.

Every time you buy a dollar-denominated share with pounds, sell it back, or receive a dividend in a foreign currency, most platforms convert at a rate marked up against the interbank rate. Charges of 0.5% to 1.5% per conversion are common, and some platforms apply the conversion to every single dividend payment, however small.

How to reduce it

• Check the actual spread, not just the headline dealing fee. It is often the larger number.
• Use a currency sub-account if your platform offers one, so dividends accumulate in their own currency instead of being converted twice.
• Consider a London-listed version of the same underlying fund, which avoids per-trade conversion even though, as covered above, it changes nothing about your underlying currency exposure.
• Trade less. Every round trip pays the spread twice. This is another quiet argument for the low-turnover approach described in our guide to rebalancing without overtrading.

8. A Practical Framework

Pulling it together into something you can act on:

• Work out your real currency exposure. Look through your funds to what they hold, not the currency they are priced in.
• Hedge overseas bonds to sterling. This is the closest thing to a default answer in the whole topic.
• Leave broad global equities unhedged if your horizon is ten years or more and you are still contributing.
• Reconsider as you approach drawdown. Shortening horizons strengthen the case for hedging.
• Minimise FX conversion costs, which are certain, recurring and entirely within your control.
• Do not try to time it. Switching between hedged and unhedged based on a view about the pound is currency speculation, and it is a game professionals lose regularly.

9. Seeing Your Currency Exposure in InvestInsight

Every recommendation above depends on knowing what your currency exposure currently is, and that is exactly the thing broker statements obscure. A UK platform shows you everything converted to pounds, which is convenient and hides the question entirely.

InvestInsight’s portfolio tracker holds each position in its native quoted currency and converts for display, so a US-listed holding, a London-listed ETF and a euro-quoted fund each keep their own identity underneath the sterling total you see. That distinction matters: it is what allows a geographic and currency breakdown to reflect what you genuinely own rather than what one platform chose to display.

The allocation view then answers the practical question directly. You can see how much of your portfolio sits behind the dollar, how much behind the euro and sterling, and whether one currency has quietly become as concentrated a bet as any single stock in the portfolio. For investors holding crypto alongside equities, where almost everything is dollar-priced by convention, that concentration is usually larger than expected.

10. Common Mistakes to Avoid

• Believing a sterling-priced fund is sterling exposure. The holdings determine the risk, not the listing.
• Leaving overseas bonds unhedged. It defeats the purpose of holding them.
• Hedging global equities by default. It costs money every year and removes a genuine crisis cushion.
• Switching hedged and unhedged based on a currency forecast. This is speculation, and it usually arrives late.
• Ignoring broker FX spreads. They are small per trade and substantial over a lifetime.
• Blaming the market for a currency result. Knowing which engine produced your return is the first step to reacting correctly.

Conclusion

Currency risk is not exotic, and it is not optional. The moment you own an overseas asset, part of your return is determined by an exchange rate, whether or not you ever think about it. The good news is that the decision framework is short: understand that your exposure comes from what your funds hold rather than how they are priced, hedge your overseas bonds, generally leave broad global equities unhedged if you have a long horizon, and pay close attention to the conversion costs your platform charges.

Above all, know what your exposure is before deciding whether to change it. If you want to see your holdings in their real currencies rather than flattened into a single number, InvestInsight’s portfolio tracker keeps that detail intact, so the currency bet inside your portfolio is one you are making on purpose.

Further reading

Currency movements are notoriously difficult to forecast. Treat any strategy that depends on predicting them with caution.

• Investopedia: currency hedging
• Investopedia: foreign exchange risk
• Bank of England: historical exchange rate data

This article is for general information only and does not constitute financial advice. All figures are illustrative. Exchange rates and interest rate differentials change continuously. Consider your own circumstances or speak to a qualified adviser before making investment decisions.