Volatility in bonds and the yen triggered calls between U.S. and Japanese officials, while traders priced in possible currency and bond market intervention.
Japan’s bond market just exploded. A selloff in its massive $7.3 trillion government bond market wiped out $41 billion in a single session and wrecked whatever calm investors thought Japan still offered.
The yield on the 30-year bond spiked over a quarter percentage point in one day. That’s not normal. Pramol Dhawan at Pacific Investment Management said, “A quarter-point surge in yields in a single session. Let that sink in.”
This is the same market that used to take weeks to move by a couple basis points. For years, Japan was where investors went for low rates and funding. Now it’s the source of chaos. Inflation has stuck.
Prime Minister Takaichi Sanae is doubling down on spending. Bond traders are now staring at yields over 4% on long-term debt, and they’re not ready for what’s coming.
Takaichi’s stimulus and election plan sends bonds into chaos
Takaichi called a snap election for February 8. She and her rivals are both pushing looser spending. That’s only made things worse. Tuesday’s crash was brutal.
The 40-year yield hit 4% for the first time ever. The 30-year jumped eight times more than its usual daily range. This isn’t a normal correction. Masayuki Koguchi from Mitsubishi UFJ said, “I don’t think Japan’s yields have gone far enough yet. This is just the beginning. There’s a chance that bigger shocks will happen.”
It’s been building for a while. The Bank of Japan ended negative interest rates back in March 2024. Since then, the JGB market has had nine separate days where losses were more than double the average.
The currency’s been a mess too. When Kazuo Ueda at the central bank said they might buy bonds again, long-term debt started to bounce back. But the yen crashed.
Then it flipped again. Rumors of government intervention started floating around trading desks in Tokyo. It got real when the New York Fed called banks to ask about the yen’s exchange rate. That’s a clear warning. U.S. Treasury Secretary Scott Bessent picked up the phone and called Finance Minister Satsuki Katayama. This is no longer just Japan’s headache.
Goldman Sachs crunched the numbers. Every 10 basis points of sudden JGB stress adds about 2 to 3 basis points to U.S. yields. That’s how Japan is now shaking global markets.
Foreign bets unwind as carry trades come under pressure
The yen isn’t just a currency. It’s a tool for funding bets worldwide. Right now, foreign money has borrowed billions using yen to gamble on higher returns elsewhere.
Mizuho Securities says up to $450 billion of trades are built on that. If Japanese yields keep climbing, that entire strategy can collapse.
And it’s already happening. In mid 2024, when the BOJ hiked again, the yen soared. Global stocks and bonds dropped fast. Investors dumped $1.1 trillion worth of carry trades. The BOJ tried to calm things down by saying it would raise rates slowly. They’re only at 0.75% now. But that message just made traders restart the same bets.
Now the bond auctions are failing. Investors have stopped showing up. Inflation is at 3.1%. That’s the fourth year in a row it’s beaten the central bank’s 2% target. Public anger over living costs forced Shigeru Ishiba out in October.
Takaichi stepped in and promised to hand out the biggest stimulus since COVID. That made yields jump even faster.
The 30-year yield climbed 75 basis points in under three months. It had taken most of 2025 to rise that much. Shinji Kunibe from Sumitomo Mitsui DS said, “Since Takaichi came into office, there’s been some disregard toward the yield movements. The fiscal situation is causing a credibility issue.”
Even the U.K. comparison has come up. Some traders are now calling this a Japan version of the Liz Truss collapse in 2022. Ugo Lancioni at Neuberger Berman said, “The danger is that Japan was a market that never moved and now you’re dealing with a level of volatility that is remarkable. You could call it a Truss moment.”
Domestic money starts coming home and foreign outflows hit
Japan’s government debt load is still massive. The debt-to-GDP ratio is 230%, the worst in the G7. When Takaichi talked about suspending sales tax on food, the bond market sank again. That wouldn’t have mattered in the old days when the BOJ bought every bond in sight. But now that they’ve pulled back, bad news actually hurts.
Foreign ownership of JGBs is climbing fast. Back in 2009, foreigners made up 12% of monthly bond trades. Now they’re 65%. They trade faster, leave quicker, and push volatility higher. Stefan Rittner at Allianz Global Investors said the market is in a fragile phase. The BOJ is pulling back, and local buyers aren’t stepping up fast enough.
The crash didn’t take much volume. Just $170 million in 30-year bonds and $110 million in 40-year bonds triggered the collapse. That’s a tiny trade for a $7.3 trillion market. But it snowballed fast.
Now, Japanese investors are starting to look inward. Around $5 trillion of Japan’s capital is invested abroad. But with domestic yields rising, that might change. Sumitomo Mitsui’s global markets head Arihiro Nagata said, “I always loved foreign bond investment, but not anymore. Now it’s JGBs.”
Japan’s second-biggest bank is shifting its portfolio. Life insurers are watching too. Meiji Yasuda, with $2 trillion in securities, says the buying opportunity is coming. Goldman Sachs says Japan’s 30-year yield could soon match the U.S. Treasury’s.
The 10-year bond is heating up too. Koguchi said it could rise another 1.25 points to hit 3.5%. That number matters. It affects everything from mortgage rates to corporate loans. Without a big shift in policy, the pressure isn’t going away.
James Athey at Marlborough Investment called repatriation flows “the elephant in the room.” He said, “The economics are already overwhelming for Japanese investors. But history says they won’t rush. It is a positive that we’ve seen some baby steps in that direction with headlines suggesting that Sumitomo is looking to increase JGB exposure.”
Don’t just read crypto news. Understand it. Subscribe to our newsletter. It’s free.
