On 9 November the Ministry of Finance published the daily breakdown of this summer’s yen intervention, and the number that changes the analysis is not the total. It is that there were three operations, not two. Traders had been pricing a two-day ambush. What actually happened was a five-week campaign with a second wave, and USD/JPY is already back at 158.30 in Tokyo.
What the MOF actually spent
| Date | Yen amount | USD equivalent | Note |
|---|---|---|---|
| 30 July | ¥7.98trn | ~$50.36bn | Single-day record; previous record was ¥6.28trn on 30 April |
| 31 July | ¥5.55trn | ~$35bn | First US-coordinated yen buying since 1998 |
| 3 August | ¥1.87trn | ~$11.8bn | Late mopping-up operation |
| Campaign total | ¥15.4trn | ~$97.2bn | Largest monthly campaign on record |
The yen had traded near 164, a four-decade low. By early September it had strengthened to 152.89, a move of more than seven big figures in five weeks — and then it gave most of it back.
Why ¥15.4 trillion did not hold the yen
Intervention changes flow. It does not change the rate differential, and the differential is what a currency pair trades.
The BOJ sits at 1.25%, the highest since 1995, after September’s 7-2 hike. The Fed sits at 3.75-4.00%. That gap pays a long USD/JPY position roughly 2.5% a year gross. At 158, 2.5% is about ¥3.95 per dollar per year, or roughly ¥0.33 a month.
That arithmetic is the whole story. ¥15.4 trillion bought an 11-yen move; carry demand only had to reclaim about a third of a yen a month to undo it. Eight weeks later, here we are. Anyone who reads a record intervention as a floor has the sign of the trade backwards: the MOF spends stock, the market collects flow.
A December where both central banks may move
Two calendar items now sit almost on top of each other.
The BOJ’s December meeting carries a live hike debate. Its chief economist Seisaku Kameda has publicly signalled a December move, and policy could be approaching 2% next year; Governor Ueda keeps flagging upside inflation risks. Separately, the FOMC meets 8-9 December, and futures price roughly 77% odds of a 25bp hike from 3.75-4.00%.
Note carefully what a double hike does: if both banks move 25bp, the differential is unchanged. The pair’s engine does not restart — the driver hands back to positioning, to carry demand, and to intervention risk. Historically it is the BOJ leg, not the Fed leg, that moves USD/JPY violently, because the yen is the funding currency in the trade. A BOJ hike shrinks the carry on every existing long; a Fed hike only reprices the destination.
The level map
- 164.00 — four-decade low, July
- 160.00 — intervention convention, not a commitment
- 158.30 — spot on 9 November, Tokyo
- 155.00 — post-intervention shelf where the August buying slowed the pair
- 152.89 — September low, the campaign’s best print
Japan has never named a level. The MOF describes its operations as a response to excessive, disorderly moves. That distinction matters: an intervention can arrive at 159 or wait for 162, and no level is guaranteed.
Constructing the trade
There are two honest theses, and they have opposite costs.
Long USD/JPY collects the differential — 2.5-2.75% a year gross before the broker’s markup, credited nightly in the swap. The risk is a 300-pip headline gap.
Short USD/JPY pays that differential every night. A two-month hold on a reversion view is a decision about carry as much as about the technicals, so check the financing table before you size it, not after.
Sizing is where small accounts get hurt. On 0.01 lot (1,000 USD notional), a 200-pip stop is a $2 loss — 20% of a $10 account’s equity. Same stop on 0.10 lot is $20, and at 30:1 that position needs about $333 of margin, so it does not exist on a small account at all. Leverage is entity-dependent: ASIC retail accounts are capped at 30:1 on majors, while offshore entities offer far more. The cap is the only thing standing between a stop and a margin call.
One more mechanic: during an intervention, price gaps. A stop-loss becomes a market order and fills wherever the book is, which can be well past your trigger. Negative balance protection stops the loss at zero; it does not stop slippage.
Calendar
- 10 November — US CPI, the single input that can move the December Fed odds
- 8-9 December — FOMC decision
- BOJ December meeting — the leg that actually matters for this pair
What would break the weak-yen case
A Fed hold plus a BOJ hike in the same window. That combination compresses the differential by 50bp in one week and removes the reason to be long dollars for carry — it is essentially what produced the September move to 152.89. The opposite combination, a Fed hike with a BOJ hold, reopens 160 with no resistance above it until the intervention book appears.
Neither outcome is a forecast. Both are calendar branches you can size for in advance.
USD/JPY is one of 26 FX pairs on UZFX, with spreads from 0.5 pips, a 0.01-lot minimum and a $10 minimum deposit. Leverage depends on the entity you are onboarded to — 30:1 for ASIC retail on majors — the platform is proprietary (Web Terminal, H5, iOS/Android/Windows/Mac, no MT4/MT5), and negative balance protection applies. None of that changes the gap risk above.
FAQ
Q: What did Japan actually spend defending the yen in 2026?
The Ministry of Finance’s 9 November disclosure shows three operations, not two: ¥7.98 trillion (about $50.36 billion) on 30 July, a single-day record; ¥5.55 trillion on 31 July; and ¥1.87 trillion on 3 August. The total, ¥15.4 trillion or roughly $97.2 billion, is the largest monthly intervention on record.
Q: Will the Bank of Japan hike in December?
The BOJ has not said so. Chief economist Seisaku Kameda has signalled a December move in public comments and Ueda continues to flag upside inflation risks. A signal is not a decision — treat it as an expectation until the statement is published.
Q: Is 160 a hard intervention line?
No. 160 is a market convention. Japan has never named a level it will defend, and the MOF frames its operations as action against disorderly moves rather than against a price.
Q: Why is the yen still weak after a record intervention?
Because intervention changes flow, not the rate differential. At 1.25% against 3.75-4.00%, long USD/JPY earns about 2.5% a year gross — around ¥3.95 per dollar annually at 158, or ¥0.33 a month. Carry reclaims an intervention one month at a time.
Q: How much does the swap cost on a short USD/JPY position?
Roughly 2.5-2.75% a year gross before the broker’s financing markup, which usually increases the debit. On 0.01 lot the nightly figure is small, but it is a one-way cost: a long hold on a short position has to earn that back before it earns anything.
Risk warning
Leveraged FX trading can lose more than the time you put into it. USD/JPY around an intervention is one of the few instruments where a stop-loss can be jumped by several hundred pips between ticks. Trade size you can carry through a gap, verify the swap and leverage terms of the specific entity you are onboarded to, and treat every number in this article as dated to 9 November 2026.