How foreign exchange distorts growth and margin in FDD — translation vs transaction exposure, constant-currency analysis, hedging P&L effects and what to normalise.
Currency is the quietest distorter of a set of accounts, and the one that catches out even experienced dealmakers. A target can report flat revenue while its underlying business grew 12%, or post a margin jump that owes nothing to operations and everything to a weakening euro. It works the other way too: a business having a genuinely good year can look pedestrian because the currency it earns in has slid against the one it reports in. For any group operating across borders, foreign exchange (FX) sits between the real economics and the reported numbers — and a Financial Due Diligence (FDD) team that takes the P&L at face value will misread both the growth story and the quality of earnings. This article walks through how FX shows up in diligence, what it distorts, and what a disciplined team normalises out.
The first discipline — and the one every interview tests — is to separate two very different effects that both get loosely called "FX".
Translation exposure arises when a subsidiary keeps its books in one currency and the group reports in another. A German parent consolidating a US subsidiary must translate dollar results into euros for the group accounts. Nothing has happened to the underlying business — the American operation sold the same units at the same dollar prices — but if the dollar moved against the euro, the consolidated figures move with it. This is an accounting artefact of consolidation, not an operating event. It changes what the number looks like in the reporting currency; it does not change what the business earned in the currency it actually operates in.
Transaction exposure is real, economic and cash. It arises when a company buys or sells in a currency different from the one it operates in — a French manufacturer paying for components in dollars but selling its finished goods in euros. Here, FX moves actual cash margins. A swing in the dollar genuinely makes the business more or less profitable, because it changes the euro cost of the components against a fixed euro selling price.
The diligence implication is the fault line the whole topic turns on: translation effects should generally be stripped out to see underlying performance, whereas transaction effects are part of the real economics and must be understood, not erased. A useful first test is to ask, for each currency the group touches, whether a 10% move would change the cash the business generates. If it would, you are looking at transaction exposure; if it only changes the reported figure on consolidation, it is translation.
The reason this distinction is not academic is that the two effects call for opposite responses. Strip out a transaction effect and you have understated the real risk the buyer is taking on — the day the currency moves, their cash margins move with it, and you failed to warn them. Leave a translation effect in and you have credited or blamed management for something they had no hand in, distorting the very performance the buyer is trying to price. Getting the classification right is therefore not a tidy-up at the end of the analysis; it is the analysis. Many first-year analysts learn this the hard way when a partner asks, of a single FX line, "is that cash or is that consolidation?" — and the honest answer is that they had not thought to ask.
Underpinning the translation question is a pair of definitions worth getting exactly right, because partners and interviewers both probe them.
A subsidiary's functional currency is the currency of the primary economic environment in which it operates — usually the currency in which it generates and spends the bulk of its cash. The group's presentational (or reporting) currency is simply the currency in which the consolidated accounts are presented. Under the standard mechanics, assets and liabilities are translated at the closing rate, income and expenses at average rates for the period, and the resulting difference parks in a currency translation reserve within equity rather than hitting the P&L. When you see a healthy operating result undermined by large swings in that reserve, that is translation at work — and it quietly tells you the group carries structural currency exposure even before you have done any operating analysis. The reserve movement is a free early signal; read it before you open the revenue file.
The headline risk in diligence is misattribution: crediting FX movements to management's skill, or blaming operations for what was really the currency.
The standard remedy is constant-currency analysis: restate each period using a single, consistent set of exchange rates — most commonly the prior-year rates — so that currency movement is held still and only the operating change remains. The gap between the reported line and the constant-currency line is the FX effect, and quantifying it cleanly is core FDD output.
A worked example makes the point. Take a euro-reporting group with a large dollar-denominated business in a year the dollar weakened:
| Metric | As reported (€) | Constant currency | FX effect |
|---|---|---|---|
| Prior-year revenue | €100.0m | €100.0m | — |
| Current-year revenue | €103.0m | €111.0m | (€8.0m) |
| Revenue growth | +3.0% | +11.0% | (8.0pt) |
| Reading | Looks pedestrian | Genuinely strong | An 8-point FX headwind |
Reported growth of 3% would read as a business running out of steam. On a constant-currency basis it grew 11%, and the eight-point gap is a currency headwind that has nothing to do with the operations a buyer is acquiring. Present the wrong line to an investment committee and you either kill a good deal or misprice it. Always show both, and label the bridge between them.
One practical caution that separates careful work from sloppy work: be explicit about which rates you used and whether you restated revenue and cost on the same basis — average or closing. An inconsistent rate basis between the top line and the cost base can manufacture a margin effect that is purely methodological and entirely fictional.
Many cross-border businesses hedge their transaction exposure with forwards or options. Hedging is sensible risk management, but it complicates the earnings picture in two ways that diligence has to unpick.
First, gains and losses on hedges can land in the P&L — sometimes in operating lines, sometimes below them — depending on whether formal hedge accounting is applied and how tightly the hedges match the underlying exposures. An unhedged FX loss in one year followed by a hedge gain the next can make underlying performance look far more volatile, or far more stable, than the operations really are. Part of the job is to find these amounts and understand where they sit.
Second, and more importantly, hedging only defers the economics; it does not remove them. A favourable hedge locked in at an old, better rate flatters current margins — but it will roll off. If today's margin depends on forward contracts struck two years ago at a rate the business will never see again, that margin is not maintainable. A disciplined team reads the hedge book's maturity profile and asks what margins look like once the protective contracts expire and the business is exposed to spot. That forward view, not the current reported margin, is what the buyer actually inherits.
Cross-border groups constantly settle balances between their own entities, and these intercompany positions generate their own FX gains and losses. Two traps recur:
The FDD team's verdict feeds the maintainable earnings and the equity bridge. As a working rule:
Unexplained, volatile FX lines sitting inside EBITDA are a classic red flag — sometimes entirely innocent, sometimes a convenient parking spot for items management would prefer you not examine.
A common prompt: "A target's reported revenue is flat, but it operates in three currencies. How do you assess whether the business is actually growing?"
A strong answer moves briskly from diagnosis to treatment:
"Flat reported revenue could easily hide real growth masked by an FX headwind, so my first step would be to rebuild revenue on a constant-currency basis using prior-year rates and look at the gap between reported and constant-currency growth — that gap is the translation effect, and it's often several points. Then I'd separate translation from transaction exposure, because they get treated completely differently: translation I'd strip out as an accounting artefact, but transaction exposure I'd keep in, because it moves real cash margins and the buyer inherits it. On margin specifically, I'd check whether the current level is propped up by hedges struck at old rates that are about to roll off, because if it is, that margin isn't maintainable. Anything sitting inside EBITDA that's FX-driven — translation, unrealised hedge marks, intercompany swings — I'd normalise out of maintainable earnings, but I'd be careful to flag the genuine transaction risk to the buyer rather than pretend it away. And I'd make sure my rate basis is consistent across revenue and cost, so I'm not manufacturing a margin effect out of methodology."
That answer shows you can tell an accounting artefact from real economics — the single distinction the whole topic turns on, and the thing an interviewer is actually testing.
FX rewards the careful and punishes the lazy. The number on the page is a blend of what the business did and what the currency did, and the entire skill is separating the two: hold the currency still, and the operating truth stands out clearly. Strip the translation noise, keep the transaction reality, model the margin past the hedges, and present both the reported and the constant-currency lines so the reader can see for themselves. Do that, and a currency move will never again be mistaken for management genius — or management failure — which on any cross-border deal is precisely the judgement the buyer is paying you for.
The Transaction Services Interview Programme (€119.99, one-time) includes a module on multi-currency diligence, with a worked constant-currency revenue bridge, a hedge roll-off template, and a checklist for normalising translation, hedging and intercompany FX out of maintainable EBITDA. Enrol today.
Hundreds of candidates prepared their interviews with this programme. Those who landed the role have one thing in common: they worked the cases before walking into the room.
