The Bank of Japan’s decision to raise its benchmark interest rate to 0.5% the highest in 31 years has sent shockwaves through global bond markets. For those of us who have watched the Land of the Rising Sun’s experiment with negative rates for years, this is the moment the ‘carry trade’ unwinds. And the Bank of England, still nursing its own inflation headache, is now staring at a spillover that could undo its careful tightrope walk.
The yield on the 10-year Japanese government bond has already jumped 10 basis points since the announcement, and global investors are recalibrating. When Japan the world’s third-largest economy starts paying more to borrow, capital flows shift. The immediate consequence is a sell-off in Western bonds, including UK gilts. The 10-year gilt yield, which had been hovering around 4.2 per cent, spiked above 4.3 per cent within hours. This is the nightmare scenario for the Monetary Policy Committee: higher government borrowing costs mean tighter monetary conditions without them lifting a finger.
Let’s be clear about what this means for the UK economy. The BoE has been fighting inflation largely through rate hikes of its own, taking Bank Rate to 5.25 per cent. But if Japanese yields rise, global investors will demand higher returns on UK debt to compensate for the opportunity cost. That pushes up mortgage rates, corporate borrowing costs, and ultimately the cost of government borrowing. Our Chancellor, already wrestling with a debt-to-GDP ratio near 100 per cent, will find the fiscal headroom evaporates faster than a pint in a City pub at closing time.
And there is the currency play. The yen has been the funding currency of choice for decades. Borrow cheap in Tokyo, invest in high-yielding assets in London or New York. Now that the cost of that yen borrowing is rising, the reverse trade begins. We are seeing the yen strengthen, which is good for Japanese importers but a headwind for UK exporters. Sterling, which had been buoyed by relatively high UK rates, could lose its edge if global investors decide the risk premium on UK assets is too high.
The BoE has been here before, of course. The 2013 ‘taper tantrum’ when the Fed hinted at reducing bond purchases sent UK yields soaring. But this time, the context is different. Then, the UK was recovering from the financial crisis with low debt. Now, we are saddled with pandemic-era borrowing and an inflation rate that, while down from its peaks, remains sticky at 4 per cent. The BoE’s own forecasts suggest inflation will not return to target until 2025. A further tightening of financial conditions via Japan could push that date into 2026.
What can the BoE do? Its hands are tied. Raising rates further to defend the pound would choke off what little growth we have. The economy flatlined in the third quarter, and the fourth quarter is likely to show a contraction. Cutting rates, as some in the City have hoped, would invite a sterling crisis, pushing up import costs and reigniting inflation. The prudent path is to hold steady and hope the Japanese move is a one-off, not a series of hikes. But markets are betting otherwise. The futures curve now prices a 25 per cent chance of a BoE rate hike in the next three months, up from zero before the BoJ decision.
For investors, the message is clear: diversify or die. UK gilts, once a safe haven, are now hostage to Tokyo. The smart money is rotating into short-dated bonds and cash, hoping to ride out the volatility. The Bank of England, for its part, will be watching the yen-dollar rate more closely than the FTSE 100. A sustained rise in Japanese yields could force a coordinated intervention by central banks to calm markets. But in a world of fractured geopolitics and fiscal profligacy, don’t hold your breath for a rescue. The lesson from Japan is one the West ignored for too long: eventually, even the cheapest money comes with a price.
