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Every conversation about mortgage rates starts the same way. The Fed raised rates. The Fed is holding rates. The Fed might raise rates again. It is all Fed, all the time — as if Jerome Powell’s successor Kevin Warsh is the single lever controlling the cost of borrowing in America.
He is not. And if you want to understand why mortgage rates are elevated, why they are likely to stay elevated, and why the conventional wisdom about a rate-cut rescue is dangerously incomplete, you need to look east. Specifically, to Japan.
What is happening in Tokyo right now is one of the most consequential and least discussed forces acting on the American housing market. It is not complicated once you understand the mechanism. But almost nobody in real estate is talking about it — which means the buyers and sellers who understand it will make better decisions than the ones who do not.
First, Let’s Separate Two Things People Constantly Confuse
The Federal Reserve sets the federal funds rate — the rate at which banks lend money to each other overnight. This affects credit cards, home equity lines, and short-term borrowing.
Your 30-year fixed mortgage rate is driven by something completely different: the yield on 10-year US Treasury bonds. These are set not by the Fed but by the bond market — by the global pool of buyers and sellers who trade US government debt every day.
Here is the simple version: when demand for US Treasuries is high, yields stay low, and mortgage rates stay low. When demand falls — when buyers step back or become sellers — yields rise to attract new buyers, and mortgage rates rise with them.
The Fed is one participant in that dynamic. But it is not the only one. And right now, the most important participant walking away from the table is Japan.
The Arrangement That Kept Your Mortgage Rate Low for Decades
For the better part of thirty years, Japan was the single largest foreign holder of US Treasury debt — sitting at approximately $1.2 trillion as recently as early 2026. Japan did not buy all that US debt out of goodwill. It was the product of a specific economic arrangement that served both countries.
Japan ran a policy of near-zero interest rates for decades — sometimes negative interest rates — to stimulate its domestic economy after the lost decade of the 1990s. With domestic Japanese bonds paying almost nothing, Japanese institutional investors — life insurance companies, pension funds, regional banks — poured money into US Treasuries instead. US bonds paid meaningfully more. The trade made sense.
The result for American homebuyers: consistent, reliable foreign demand for US debt that kept Treasury yields lower than they would otherwise have been, which kept mortgage rates lower than they would otherwise have been. Every time a Japanese life insurer bought a US Treasury bond, it was effectively subsidizing American mortgage rates.
That arrangement is now unwinding. And the unwinding is accelerating.
What Japan Changed and Why It Matters Right Now
The Bank of Japan spent decades holding domestic interest rates at or below zero. Starting in 2024, it began reversing course. Japanese government bond yields have now risen to 2.73% on 10-year bonds — a 28-year high. The 30-year Japanese government bond yield recently broke through 4% for the first time ever.
Why does that matter for you? Because once Japanese bonds started paying meaningful yields, the entire logic of the carry trade reversed. Japanese institutions no longer need to send their money to America to earn a return. They can earn competitive yields at home, in their own currency, without taking on the foreign exchange risk that comes with holding dollar-denominated assets.
The result has been a historic withdrawal from the US Treasury market. Japanese investors sold a net $29.6 billion in US government, agency, and municipal bonds in the first quarter of 2026 alone — the largest quarterly reduction in nearly four years, with sales accelerating each month. February saw ¥3.42 trillion in sales. March saw ¥4.12 trillion. The pace is not slowing. As one senior portfolio manager at Federated Hermes put it, Japan is “removing a historically reliable buyer from markets already navigating large fiscal deficits.” Crypto BriefingCNBC
The new money being put to work in Japan will not be going overseas. It will stay home. And Japan holds approximately $1.2 trillion in US Treasuries. If even a fraction of that continues flowing back to Tokyo, the impact on US Treasury yields — and therefore on mortgage rates — is substantial. Fortune
TD Economics has projected that Japan’s tapering of US bond investment could push US 10-year yields higher by 20 to 50 basis points over the medium term. A 50 basis point increase in 10-year yields translates directly into higher mortgage rates, higher corporate borrowing costs, and higher costs for the federal government to service its own debt. Crypto Briefing
The Carry Trade Unwind — And Why It Could Get Worse
There is a secondary mechanism that makes this story even more significant: the yen carry trade.
For years, global investors borrowed money cheaply in Japanese yen — because rates were near zero — converted it into dollars, and invested it in higher-yielding US assets including Treasuries. This trade amplified Japanese demand for US debt beyond just direct Japanese institutional buying.
As the Bank of Japan raises rates and the yen strengthens, that carry trade unwinds. Investors who borrowed in yen to buy dollar assets now have to sell those dollar assets, convert back to yen, and repay their yen loans. That means selling US Treasuries. More supply hitting the market, less demand absorbing it — yields rise further.
The American Enterprise Institute has warned that the prospective unwinding of the Japanese carry trade comes at an awkward time and that absent a rethink of US budget policy, we should brace for a meaningful rise in US Treasury bond yields. AEI
What This Means for Mortgage Rates in Boston and on Cape Cod
Here is the honest translation for anyone trying to make a real estate decision right now.
The narrative that mortgage rates will fall meaningfully when the Fed cuts rates is built on an incomplete understanding of how rates are actually set. Even if Warsh’s Fed pivots and begins cutting the federal funds rate — which, after last week’s press conference, looks less likely, not more — the 10-year Treasury yield that drives mortgage rates is being pulled upward by forces the Fed does not directly control.
Japan leaving the US Treasury market is one of those forces. It is structural, it is accelerating, and it does not respond to Fed press conferences. Higher Treasury yields ripple throughout the American economy — mortgage rates stay elevated, corporate borrowing becomes more expensive, and the federal government’s own interest payments continue consuming an ever-larger share of national expenditure. Asia Times
The buyers who are waiting for a return to 5% or sub-5% mortgage rates are waiting for a set of conditions that requires not just a cooperative Fed, but a reversal of the Japanese repatriation trend, a resolution of the US fiscal deficit problem, and a stabilization of the geopolitical environment that has been driving energy prices and inflation. None of those conditions are imminent.
What is imminent is more of what we have been living with: mortgage rates in the mid-to-upper 6% range, a cautious buyer pool, deliberate decision-making, and a market that rewards precision over wishful thinking.
The One Thing to Take Away
The Fed is not your mortgage rate. Your mortgage rate is global demand for US debt. And the most reliable buyer of that debt for thirty years is heading home.
That is the story nobody in real estate is telling. Now you know it.
If you want to work through what it means for your specific buying or selling decision in Boston or on Cape Cod, that is the conversation we have every day.
508-420-8800 · thegriffin.co
Griffin Realty Group serves buyers and sellers across the Boston metro and Cape Cod luxury real estate markets.
