Why a hawkish Fed helped Britain's not-so-British index

The Federal Reserve raised rates for the first time in three years on Wednesday, lifting its target to 3.75–4% under a chairman determined to show inflation is being fought. Wall Street slid on the hawkish message. London's FTSE 100, by contrast, closed slightly higher, at around 10,688. That looks like a puzzle: why would a British index cheer the very tightening that spooked America?

The answer is that the FTSE 100 is not really a bet on Britain. Its members—BP and Shell, the miners, the global banks, the household names that sell soft drinks and soap to the world—earn a substantial majority of their revenues abroad, much of it in dollars. In the index-maker's own framing, it reads less like the British economy and more like a proxy for the global one. That changes what a Wall Street decision does to it.

The trade runs through the currency

The mechanism runs through the pound. A hawkish Fed lifts the dollar, which pushes sterling down—the currency had already slid to a five-week low near $1.35 as markets priced an American hike. For a company that earns its money in dollars and reports it in pounds, a weaker currency is a windfall: every dollar of revenue is suddenly worth more at home. The same tightening that compresses the valuations of rate-sensitive American growth stocks inflates the sterling value of London-listed multinational earnings.

Oil does the rest. The Middle East conflict has pushed crude above $100 a barrel, and the FTSE 100 is stacked with energy and mining producers that collect those high prices directly. The index therefore rallied for the very reasons America's fell: a strong dollar economy and expensive commodities.

The other central bank is next

The more consequential question is what the Bank of England does on Thursday. Policymakers are expected to hold Bank Rate at 3.75%—a sixth straight hold in 2026—in a 6–3 vote, with every economist polled by Reuters expecting inaction. The logic of the divergence is instructive. UK inflation has crept back to 3.1%, but it is being driven by energy. Raising borrowing costs cannot fix an oil price, so the Bank has been "looking through" the shock, waiting for signs that it is seeping into wages rather than treating the swell in fuel bills as a reason to tighten. That is a genuine institutional choice, not timidity: two central banks looking at the same global oil shock can reasonably reach different verdicts, because the underlying economies are priced, so to speak, in different currencies.

Yet the market has already decided the divergence will not last. Roughly a third odds were priced on a September hike and near-certainty on a move in November, as attention turns to the fiscal position the government will set out in its autumn budget. If oil stays above $100 and the Bank is forced to act anyway, the pound firms, and the same mechanism that has been lifting the index reverses direction.

What this means for an American investor

For a US retail investor, the practical lesson is about what the FTSE actually sells. Buying UK equity exposure—the common route being a dollar-denominated ETF such as iShares' MSCI United Kingdom fund—is not a quiet way to own the British high street. It is a concentrated wager on the dollar, on oil, on global banks and miners, alongside a value tilt that currently yields roughly 3%.

That tilt has been working. But the divergence that fuelled it is priced, not free. The easy part of the currency trade is behind: the Fed has signalled at least one more hike this year, sterling has already fallen, and the FTSE sits within a whisker of its records. The identity of the two central banks' paths is the variable to watch—because when the pound turns, the same index that gained on a hawkish Fed can just as cheerfully give the gains back.