Japan's highest-yielding government bond is the 25-year, not the 40-year — on 30 of 33 days since September
We have saved Japan's official yield curve every day since 1 September; the Ministry of Finance keeps only the current month. The curve tops out at 25 years, and since September the short end has risen while the long end fell.
AI-assisted, human-reviewed sourcing. Figures are pulled programmatically from the official sources listed at the end of this article and checked by an editor before publication.
jgb yieldsjapan yield curvejapan government bondsjgb 30 yearjgb 10 yearjapan rates
In most bond markets the longest bond pays the most. Japan’s does not. On Japan’s official yield curve the highest point has sat at 25 years, above both the 30-year and the 40-year, on 30 of the 33 business days since 1 September.
We can count that because we kept the numbers. Japan’s Ministry of Finance publishes its constant-maturity yield curve as a file that holds only the current month; when a new month starts, the old days go. We have saved it every day since 1 September.
Where the curve peaks
On 21 October the long end looked like this:
| Maturity | Yield, 21 Oct 2026 |
|---|---|
| 20 years | 3.726% |
| 25 years | 4.008% |
| 30 years | 3.980% |
| 40 years | 3.994% |
The 25-year pays about 3 basis points more than the 30-year and 1 more than the 40-year. The gap is small, but it has held: on 30 days of 33, the 25-year was the top of the curve. On the other three, the 40-year was.
Short end up, long end down
Over the same seven weeks the curve flattened from both ends.
| Maturity | 1 Sep | 21 Oct | Change |
|---|---|---|---|
| 1 year | 1.527% | 1.657% | +13.0bp |
| 2 years | 1.802% | 1.914% | +11.2bp |
| 5 years | 2.280% | 2.309% | +2.9bp |
| 10 years | 2.987% | 2.923% | −6.4bp |
| 20 years | 3.859% | 3.726% | −13.3bp |
| 30 years | 4.131% | 3.980% | −15.1bp |
One- and two-year yields rose by more than ten basis points. Twenty- and thirty-year yields fell by more than ten. The pivot sits between five and ten years. The gap between the 30-year and 10-year narrowed from 114 to 106 basis points.
Why keep a file the ministry throws away
This is not hidden data; the ministry publishes it daily. But it publishes it one month at a time, and a question such as “how often did the 25-year top the curve this autumn?” needs every day, including the ones that have already dropped off the official file. Keeping them is the whole of the method.
We do not say here why the curve has this shape. Issuance by maturity, central-bank buying and the demand of long-term investors all play a part, and this count does not separate them. It establishes the shape and how steady it has been.
Ministry of Finance, Japan, JGB constant-maturity interest rates, saved daily by SeoulMarkets from 1 September to 21 October 2026 (33 business days). Not investment advice.
Data & Verification Notes
- Data as of
- Sources
- Cross-checks
- On 30 of 33 business days from 1 September to 21 October 2026 the 25-year yield was the highest point on the curve; on the other 3 it was the 40-year.
- 21 October 2026: 25Y 4.008%, 30Y 3.980%, 40Y 3.994% — the 25-year sits above both longer maturities.
- 1 September → 21 October: 1Y 1.527% → 1.657% (+13.0bp); 2Y 1.802% → 1.914% (+11.2bp); 5Y 2.280% → 2.309% (+2.9bp); 10Y 2.987% → 2.923% (−6.4bp); 20Y 3.859% → 3.726% (−13.3bp); 30Y 4.131% → 3.980% (−15.1bp).
- 30-year minus 10-year spread: 114.4bp on 1 September, 105.7bp on 21 October.
- Excluded figures
- Why the curve is shaped this way. Supply by maturity, Bank of Japan purchases and investor demand all matter; we did not test any of them.
- Days before 1 September 2026. The Ministry's file covers only the current month, and we began saving it then; earlier daily values are not in our archive.
- Any forecast of rates or of Bank of Japan policy.
- This is not investment advice.
The full dataset behind these figures — every listed company, every row — is available to license. SeoulMarkets data for licence →
Not investment advice. SMarkets publishes data journalism for general information only. Nothing here is investment advice, a recommendation, or an offer to buy or sell any security — any investment you make is at your own risk and responsibility. Figures are derived from official public data sources and may be revised by the issuing agency. Verify independently before acting.
← More Rates