Sterling’s Silent Hand: Auditing the Currency Exposure in a UK Portfolio

Currency risk is rarely the first item on a UK investor’s agenda. It should be closer to the top. For anyone measuring returns in sterling, the exchange rate is not a side issue; it is part of the return calculation. A fund can produce a respectable gain in its local market and still deliver a disappointing outcome in pounds if sterling has strengthened. The reverse is equally true. In 2026, with UK gilt yields still shaping the savings landscape and global equity valuations sensitive to rate expectations, that translation effect deserves a more disciplined look.

Why sterling is the silent variable

Total return for a UK investor is a two-part equation: the change in the underlying asset, plus the change in the currency in which it is denominated relative to sterling. The second part is easy to overlook because it does not appear as a line item on many fund factsheets. It nevertheless feeds directly into the number that matters to a UK-based investor.

The FTSE 100 adds a layer of complexity. The index is quoted in sterling, but many of its constituents earn revenue in dollars, euros and other currencies. A weaker pound can flatter translated earnings and support the index; a stronger pound can do the opposite. That does not make the FTSE 100 a pure domestic play, nor a pure currency hedge. It is a mixed exposure, and the mix differs by company. A miner, a pharmaceutical group and a domestically focused retailer may all sit in the same index while carrying very different currency profiles.

Where unintended bets hide

Global equity funds, US index trackers and investment trusts often carry a currency exposure that is hidden by the fund’s base currency. A fund priced in sterling may hold dollar assets unhedged. A hedged share class may sit alongside an unhedged one under the same brand. The label on the factsheet is not the exposure.

Hedging is not free insurance. It is typically implemented through forward foreign exchange contracts, and its cost is embedded in interest-rate differentials. When UK rates are high relative to the currency being hedged, the cost can be material; when the differential moves the other way, hedging can even add to returns. That makes the decision time-sensitive and share-class-specific. A hedged class that looked expensive two years ago may look differently priced today, and vice versa.

There is also a difference between translation exposure and economic exposure. A UK-listed multinational with dollar revenue and sterling costs has a different currency profile from a US Treasury bond held in a sterling-denominated fund. The first may benefit from a weaker pound through translated earnings; the second is a purer currency bet. Investors who treat both as simply overseas exposure may misread the risk they are running.

A practical audit for UK portfolios

1. Set the baseline. Start with liabilities, not labels. If spending, income needs and future commitments are in sterling, sterling is the benchmark. A portfolio that looks diversified in asset terms may still be concentrated in currency terms.

2. Look through the fund. Identify the currency of the underlying assets, not the denomination of the fund. A sterling-priced global tracker may hold mostly dollar assets. A sterling-hedged version may hold the same assets but with a very different return profile.

3. Separate translation from economics. Ask where revenues and costs are earned, not just where the company is listed. A FTSE 100 constituent with global revenue and a sterling cost base is not the same currency exposure as a UK domestic bank.

4. Map concentration. If several funds all hold the same mega-cap US technology names, the portfolio may have a larger dollar bet than the headline allocation suggests. Currency exposure can compound through overlapping holdings.

5. Stress test. Ask what a 10% move in sterling would do to portfolio income and capital values. The exercise need not be precise. Its purpose is to reveal where the portfolio is most sensitive.

6. Price the hedge. Compare hedged and unhedged share classes after costs, tracking difference and liquidity. A hedged class that reduces volatility but costs more than the investor expects may not be the obvious improvement it appears to be.

When hedging earns its keep

Hedging tends to be most defensible when the investor has a known sterling liability in the near term. A pension drawdown plan, a school fee commitment or a property purchase in the next few years creates a clear reason to reduce currency volatility. In those cases, hedging is less about forecasting sterling and more about matching assets to liabilities.

For long-horizon investors, the case is less clear. Currency moves can diversify returns, and unhedged global equity exposure may benefit from sterling weakness over long periods. Hedging can smooth the ride, but it also removes a source of diversification and introduces a cost that compounds. The decision should reflect time horizon, spending needs and the price of the hedge, not a forecast of sterling.

The discipline of knowing the bet

Currency is not an optional extra in a UK portfolio. It is a live exposure that sits inside global funds, FTSE 100 earnings and the choice between hedged and unhedged share classes. The aim is not to eliminate currency risk but to know where it sits, why it is there and what it costs to change. Investors who audit that exposure before sterling moves again are better placed to judge whether their returns are coming from asset selection or from the currency translation they never intended to make.