The FTSE 100 is one of the most-quoted indices in international financial media, and one of the most consistently misread. Its constituent companies are London-listed, but the aggregate revenue of the index has for decades come predominantly from outside the United Kingdom. Reading the FTSE as a bet on the UK domestic economy is the single most common error in international equity commentary — and one that shapes both retail understanding and, at times, professional allocation decisions.
The revenue composition
Aggregated across all 100 constituents, roughly 75% of FTSE 100 revenue is generated outside the UK. The largest single geographical exposure after "rest of world" is often the United States (typically 20–25% of aggregate revenue), followed by Europe ex-UK, then emerging markets, then domestic UK.
The reason is compositional. The FTSE's largest weightings are in sectors — global energy majors, global miners, global banks, global pharmaceuticals, global consumer goods — whose businesses are structurally international. Shell, BP, Rio Tinto, HSBC, GSK, AstraZeneca, Unilever, Diageo — each of these is a name most global investors would recognise, and each derives the vast majority of its revenue from outside its country of listing.
The domestic-UK portion of FTSE revenue comes primarily from a smaller subset: some banks, retailers, homebuilders, and utility companies whose businesses are meaningfully anchored to the UK economy. In aggregate, these represent perhaps 20% of the index.
What this means for currency
Because so much of the FTSE's earnings comes in non-sterling currencies, the index has a substantial inverse correlation with the pound. When sterling weakens against major currencies, FTSE earnings translated back into sterling rise, all else equal — the index tends to rise in sterling terms on pound weakness. When sterling strengthens, the reverse.
This is why the 2016 Brexit vote produced an initial FTSE rally even as broader UK economic sentiment collapsed: the sterling depreciation that followed the vote directly boosted the translated earnings of the international revenue base. Reading that response as "the market was optimistic about Brexit" mistakes the mechanical currency translation effect for a sentiment signal.
The FTSE 250 as the actual UK domestic index
The FTSE 250 — the next 250 largest UK-listed companies below the FTSE 100 — is a much closer proxy for the UK domestic economy. Its constituents are on average smaller, more UK-focused in revenue, and more sensitive to domestic conditions.
A reader who wants a true "UK domestic equity" exposure is much better served by the FTSE 250 than by the FTSE 100. The two indices' correlation is meaningful but far from perfect, and they diverge exactly at the moments when a UK-specific view matters most.
Sector concentration and its consequences
The FTSE 100 is heavily concentrated in a small number of sectors that have been out of favour globally for much of the past decade. Financials, energy, materials, and consumer staples together typically account for over 60% of the index. Technology is a very small share (usually below 2%, dominated by a handful of names).
This composition explains much of the FTSE's underperformance versus the S&P 500 over the 2010s. A market dominated by sectors that were underperforming globally would have underperformed regardless of listing venue. The composition also explains why the FTSE has done comparatively well during periods when commodity and financial sectors have led — early 2022, for example.
The dividend character
The FTSE 100 has historically had one of the highest dividend yields of any major developed-market index — often 3.5–4.5% aggregate yield, versus 1.5–2% for the S&P 500. The yield reflects the mature-industry composition and, in some cases, capital-return policies that skew heavily toward dividends over buybacks (unlike the US pattern of the past decade).
For a total-return-oriented investor, this changes the way FTSE performance should be measured. Price-return comparisons between the FTSE and the S&P substantially understate the FTSE's total return, because the dividend component has been a much larger share of the total.
The listing-venue question
An ongoing structural question for London is whether it can continue to attract new listings and prevent the departure of existing ones. Several notable UK-domiciled companies have moved their primary listings to New York over the past several years — a phenomenon widely discussed in UK financial press but of somewhat limited near-term impact on the FTSE's composition, since the departing companies have generally been smaller.
The longer-term implication is more consequential: if the trend continues, the FTSE could progressively drift toward the older, more mature, less growth-oriented composition that would leave it structurally underperforming more diversified indices. Whether policy responses (listing reforms, tax adjustments) succeed in reversing the trend is one of the more interesting structural questions in UK equity markets.
The frame this implies
Read the FTSE 100 as a globally-diversified basket of large-cap value-and-yield companies that happen to be listed in London. Do not read it as a bet on the UK economy. If you want the UK economy exposure, use the FTSE 250 or specific domestic-focused names. If you want global value exposure with a heavy tilt toward mature industries, the FTSE 100 is one of the few available packages of exactly that.
Educational content only. Not investment advice.