A currency puzzle unfolds: sterling gains as UK-Japan rate signals clash, despite a widening policy gap.
Two G7 central banks moving in opposite directions this week might seem like a straightforward bet for the currency markets. Yet the UK pound against the yen has not followed the expected pattern. Over the past year, traders have paid more attention to fiscal policy risks and bond flows than to plain interest-rate differentials, and that dynamic continues to shape the cross-rate.
Here’s the bigger picture: since mid-2024, the gap between the Bank of England and the Bank of Japan on policy rates has narrowed dramatically—by about 165 basis points. That squeeze is poised to exceed 200 basis points this week, as the Bank of England is anticipated to trim rates again to around 3.75%, while the BoJ is expected to lift its rate to about 0.75% in the following day.
But the sterling/yen pair has appreciated more than 1% against the yen in these 18 months and is up roughly 5% from the middle of the year, marking the strongest levels for the pound against Japan’s weaker currency in 17 years.
Much of this movement reflects a broader trend: the yen has been weakening across the board, a development that has sparked political controversy in Japan as some observers view it as a deliberate policy to spur inflation. Since the pandemic, the yen has tumbled, with Japan’s real effective exchange rate sinking about 30% to its weakest in over five decades. The currency even flirted with levels not seen since the 1980s against the dollar.
Yet the pound isn’t simply riding the yen’s decline. The sterling’s real effective exchange rate has risen about 10% since 2020 and has gained an additional 1% this year, indicating that UK strength is not solely tied to Japan’s weakness.
Even if markets are ahead of the curve on currencies, bond markets tell a parallel story. The two-year yield gap between UK gilts and Japanese government bonds has halved since mid-2023 and continues to narrow, yet the sterling/yen rate has climbed by about 14% in the same period.
Inflation-adjusted, or real, yield spreads have followed a similar pattern. Earlier this year, real yields favored sterling, but those spreads narrowed by roughly 60 basis points. In the long end of the curve, where financial market turmoil has been most pronounced this year, the 30-year yield gap between the UK and Japan has swung by about 120 basis points since January.
So why the persistent rise in sterling/yen? Brokerage and investment flows offer a compelling part of the answer.
On the surface, the key macro figures don’t reveal a clear signal. The OECD’s latest outlook shows UK and Japan expected to post roughly similar real GDP growth this year, with Britain slightly edging ahead in growth over the next couple of years. Inflation in both economies is forecast to converge near 2.1% by 2027.
If rate gaps alone don’t drive the currency moves, fiscal policy trajectories do some of the heavy lifting. Despite recent political noise around Britain’s budget, the UK’s fiscal stance is tightening, while Japan’s new leadership has embraced renewed stimulus spending.
That divergence in budgets helps explain why the Bank of England and the BoJ are charting different courses this week. The UK faces politics around spending restraint and tax decisions, whereas Japan leans toward expansion, raising questions about how much room Tokyo has to maneuver its already enormous debt.
A crucial driver may be the behavior of Japanese bond investors, who appear to be a central force behind cross-border flows. Japanese buyers have become a substantial share of the UK gilt market, and October saw Japanese funds purchasing the largest quantity of UK sovereign debt in more than four years. This activity occurred even as UK long-dated debt offered a modest pickup in yield relative to domestic bonds.
Meanwhile, political turmoil in Japan contributed to a retreat from domestic markets, amplifying cross-border capital movements. In the end, it is not merely the direction of rates that matters, but the scale and direction of investment flows that shape the currency market’s latest moves.
The viewpoints expressed here reflect the author’s analysis and do not necessarily represent Reuters’ institutional stance. For readers following these developments, the takeaway is clear: exchange rates are increasingly influenced by fiscal policy paths and investor behavior across borders, not solely by central-bank rate decisions.
Would you agree that fiscal policy signals and cross-border investment flows are the dominant forces behind the sterling/yen dynamic right now, or do you see another driver taking precedence? Share your thoughts in the comments.
