Currency exposure is a decision you make by ignoring it

The theory of currency risk is well covered elsewhere. This is about the version you meet in practice.

Two returns in one number

Buying a fund of overseas companies gives you the return of those companies plus the movement of their currency against yours. A market that rises ten per cent while its currency falls ten per cent against yours produces roughly nothing for you.

The reverse also happens, and it has periodically been the larger part of the return experienced by domestic investors. The fund's reported performance in its own currency is therefore not the return you received.

Hedging removes most of it, for a price

Currency-hedged share classes use forward contracts to offset exchange rate movement, delivering something closer to the local-currency return. The hedge is not free: it carries transaction costs and reflects the interest rate difference between the two currencies, which can help or hurt. Hedging is generally imperfect and is reset periodically, so it reduces rather than eliminates currency effects.

Both hedged and unhedged versions of the same fund commonly exist, and the difference between them over a decade can be substantial.

Equities and bonds are usually treated differently

For overseas bonds, currency movement can easily exceed the entire yield, which is why hedged versions are common and often preferred. For equities, currency movement is smaller relative to the asset's own variability, and unhedged exposure is more often accepted. This is a widespread convention rather than a settled finding, and reasonable practitioners disagree.

The important point is that leaving it unconsidered means accepting whichever exposure the fund happens to have.

The currency you will spend is the reference point

Someone who will retire and spend in one currency has liabilities in that currency, and holdings in others introduce mismatch. Someone who expects to move country, or whose costs are substantially in another currency, has a different reference point. Framing it as matching assets to future spending is more useful than framing it as a forecast about exchange rates.

Nobody reliably forecasts exchange rates, which is why the decision should not rest on a view about them.

Domestic companies are not domestic exposure

Large listed companies frequently earn most of their revenue overseas, so a home-market index can carry substantial foreign currency exposure indirectly. This means the distinction between domestic and international holdings is less clean than fund labels suggest.

In numbers, currency effects on such companies flow through profits rather than through the share price directly, which makes them harder to see. The practical consequence is that home bias provides less currency matching than people assume.

Rates, thresholds and rules differ by country and change often — check current figures before acting.

Costs and tax add a layer

Buying overseas holdings can involve foreign exchange charges on each transaction, and platform spreads on currency conversion are frequently wide. Some jurisdictions apply withholding tax to dividends from overseas holdings, sometimes recoverable and sometimes not, depending on treaties. These frictions are separate from currency movement and accumulate quietly.

The arithmetic is straightforward: how any of this applies to you depends on your residence, your platform and your holdings, which makes it a question for a qualified adviser rather than a general rule.

The takeaway

Decide whether you want the currency exposure. Not deciding means holding whatever your funds happen to carry.

The decision is rarely about picking the best option — it is about avoiding the expensive one.