155.28 on a Ten-Basis-Point Move (3 September 2026): The Yen's Best Day Since July Came From Both Central Banks at Once — and the Official Intervention Bill Is Now ¥15.4trn

For the first time in this cycle, both ends of the interest-rate gap that sets the yen's level moved in the yen's favour on the same day. Governor Kazuo Ueda pointed the Bank of Japan at upside price risks on Tuesday, board member Hajime Takata called for "nimble" hikes on Wednesday, and on Thursday Fed Governor Christopher Waller said he was inclined to hold — and the dollar fell 3.2% against the yen, from a Tokyo high of 160.39 on Wednesday to 155.28 in New York on Thursday, the yen's strongest since 3 August. The number that did not move much is the one this page has argued about since July: the US-Japan two-year yield gap closed roughly ten basis points, to 2.49 points. Separately, the Ministry of Finance has now put the official intervention bill for 30 July to 26 August at ¥15.4trn — more than the estimates said.

This page was published on 2 July, has tracked the July intervention and the August inflation data since, and is rewritten here on 4 September around the reversal. It has been shortened as well as updated: the layers of dated commentary that accumulated through August have been cut back to the mechanism and the numbers that still bear on it.

What actually happened: 160.39 on Wednesday, 155.28 on Thursday

The Bank of Japan's market desk publishes its own spot record every afternoon, and it is the cleanest way to see the turn without relying on anyone's chart.

Source: Bank of Japan daily foreign exchange rates.

Read down the last two rows and the sequence is unambiguous. The dollar opened Wednesday's Tokyo session at 160.20 and printed the week's high at 160.39 — above the 160 level the market treats as an intervention threshold — then fell for the rest of the week. By Thursday's 17:00 Tokyo fix it was at 157.03, a 2.66 yen move from the previous close and the first time in a month the pair had broken 157. The move continued after Tokyo closed: CNBC, citing LSEG data, put the intraday low at 155.28, the strongest the yen had been since 3 August, with the pair trading at 155.40 as it wrote.

That 3 August reference point is worth holding onto, because it is where the post-intervention peak sat. The Bank's own record for that day shows a low of 155.20. Thursday came within eight sen of undoing a month of decay in two sessions.

The trade-weighted measure agrees. The Bank's yen index — the currency's nominal effective exchange rate, not just its dollar rate — went from 72.10 on 1 September to 72.72 on 2 September, against a post-intervention high of 73.99 on 3 August and a July trough of 71.33. This was not a dollar story happening to the yen. The yen rose against the euro and sterling on Thursday as well.

Was it intervention? What the Bank of Japan's own turnover data says

Wednesday's roughly 1% spike arrived without warning and immediately produced the question Tokyo has trained the market to ask. There is a way to interrogate it that does not depend on anyone's opinion.

Alongside each daily fixing sheet, the Bank of Japan publishes Tokyo spot US dollar/yen turnover for the previous business day. Intervention is, mechanically, an enormous trade. It shows up.

Source: Bank of Japan, turnover of previous business day.

The confirmed solo operation moved fourteen times an ordinary day's volume through the Tokyo market. The confirmed joint operation moved roughly five times. Wednesday 2 September moved 1.6 times the previous day and a little over twice a quiet late-August session — elevated, clearly, but an order of magnitude short of what an operation looks like in this series.

Market participants arrived at the same place from other evidence. ING's global head of markets Chris Turner noted doubt about Wednesday "given the lack of dislocation in the FX electronic matching systems at the time". Takuji Okubo, chief economist at Japan Macro Advisors, told CNBC that Thursday's move was "possible" as intervention, "but I do not think [the Ministry of Finance] has done this kind of small stealth intervention in recent history. So it is probably just a reaction to BOJ Governor Ueda's comment cementing the high likelihood of a BOJ rate hike in September."

Tokyo, for its part, has not stood down. Vice Finance Minister for International Affairs Atsushi Mimura said on Thursday that authorities were "neither satisfied nor reassured" by recent moves and "remain on a state of heightened alert", according to Reuters. And Deutsche Bank analysts flagged the calendar: "The market is on watch with chatter that intervention could occur around the thin trading conditions of the 'Silver Week' holidays that see markets closed for three days immediately after the BOJ meeting."

The gap: both ends moved the yen's way — and it closed ten basis points

This page has made one argument since July: the yen's level is set by a difference, and a difference only moves when one end moves relative to the other. On 28 August that produced the worst possible configuration — Japanese inflation data all but sealed a hike, then Kevin Warsh spoke at Jackson Hole and the US two-year rose 14 basis points, so the gap finished the day wider than it started it. Our note on the keynote takes that session apart.

The first week of September ran the same machinery in reverse.

Sources: US Treasury daily par yields and the Ministry of Finance JGB series.

Both legs contributed, which is the genuinely new part. The Japanese two-year rose about five basis points on 2 September as the Board's own members made the September case. The American two-year then fell five basis points on 3 September when Waller made the case for waiting. Net, the differential closed just under ten basis points across two sessions and reached 2.490 points — the tightest reading in the sequence this page has tracked, narrower than the 2.50 of 27 August.

Now hold that against the currency. Ten basis points of differential accompanied a 3.2% move in the exchange rate. Those two numbers are not commensurate, and pretending otherwise is how people end up surprised a month later. What repriced on Thursday was not the carry a short-yen position earns today; it was the market's estimate of what that carry will be after 18 September. Expectations moved. Cash flows did not, or barely.

That distinction is the whole lesson of August. After the July operation the yen went from 163.99 to 155.20 without the differential changing at all, and it handed most of that back inside a month for the same reason. A level bought with expectations has to be paid for later with realised policy, and the invoice arrives in the middle of September.

¥15.4trn: the official bill is larger than the estimates were

While the market argued about stealth operations, the Ministry of Finance quietly settled the arithmetic on the ones that actually happened. Its monthly release, published 28 August, puts foreign exchange intervention for the reporting window of 30 July to 26 August 2026 at ¥15,399.3bn — ¥15.4trn, about $98bn (Ministry of Finance).

That is larger than the number this page previously carried, and the discrepancy is informative. Estimates derived from Bank of Japan current-account data put 30 July at roughly ¥8.45trn and 31 July at about ¥5.33trn — ¥13.8trn for the two sessions everyone watched. The official window total exceeds that by around ¥1.6trn.

There are only two explanations and the Ministry has not yet supplied the one that would settle it, because the day-by-day breakdown appears only in the quarterly release. Either the current-account estimates understated the July sessions, or yen buying continued into August after the market had concluded the operations were over. The second reading is not exotic: it would explain why the retracement through mid-August was as orderly as it was. Until the daily data lands, the honest position is that the total is known and its distribution is not.

Why the intervention was never the lever

The firepower question was answered in August and it is worth keeping only in summary. Goldman Sachs Research estimates that of Japan's roughly $1trn in US dollar reserves, about $200bn sits in cash or cash equivalents — close, on the same bank's estimate, to the size of the operation already conducted. "They already have at their disposal enough to do another couple rounds of what we just saw," strategist Karen Fishman said on the bank's Exchanges podcast, adding that Tokyo has "plenty of capacity to keep intervening if they wish". The Ministry has also said it plans to use the Federal Reserve's FIMA repo facility, which lets it raise dollars against its Treasury holdings rather than by selling them — severing the loop in which funding an intervention pushes US yields up and widens the very gap the intervention is fighting.

So the constraint was never the war chest. It is that an operation buys a price without buying the yield differential that sets the price. While a dollar deposit pays roughly two and a half points more than a yen deposit, the carry incentive regenerates the selling every day, and the authorities have to keep paying to lean against a flow that costs the market nothing to renew.

Which is why 3 September matters more than any intervention total. A rate rise is the operation that pays for itself, and it costs Tokyo nothing in reserves. The Board's own reasoning has been pointing there for months: the July Summary of Opinions records members judging that "risks to prices are significantly skewed to the upside", that "the pace of policy interest rate hikes will be faster than market expectations", and that the objective has shifted from lifting inflation to 2% to "avoiding further upward deviation". A weak yen has become an argument for the hike that would strengthen it. The mechanics are set out at greater length in our explainer on how currency intervention works.

The September sequence now decides whether this holds

Two meetings decide it, and their order matters as much as their content.

The Federal Reserve goes first by roughly 48 hours, so the Bank of Japan will set policy knowing the American answer while the Fed sets policy without the Japanese one. Asymmetric information about a rate gap is not a footnote — it is the difference between one central bank reacting and both guessing. One further scheduling quirk: Japan's national August consumer price index is released on 18 September, the same morning the Board announces.

The asymmetry in that table is the practical point. At 98% priced on the Japanese leg, a hike delivers very little that is not already in the price, while a hold would be violent — Fishman's "renewed downward pressure on the yen" case, now at a far higher level of expectation than when she said it. The variable with room to move is American, and it starts moving at 8:30 Eastern on Friday. Our note on the August employment report sets out the consensus (+53,000, unemployment 4.1%, average hourly earnings +0.3%) and why the household survey complicates a soft print.

There is also a path nobody chooses. The yen is a funding currency in calm markets — the thing you borrow — and flips to a safe haven in a crisis as carry trades unwind violently, as our anatomy of the 2024 unwind describes. A volatility spike remains the fastest possible reversal, and no authority needs to spend a yen to cause it.

The second channel: an energy bill that is still working against the yen

The rate gap explains the trend. A second factor explains why the yen has had so little natural support: commodities, through Japan's oil-import bill. Japan imports almost all of its energy, so dearer crude widens the import bill and creates real-money yen selling as importers buy the dollars to pay for it.

That channel has re-tightened. Brent sat near $96 in early September, on course for its biggest weekly gain since July, as Middle East tensions returned to the front of the tape — the shipping mechanics are in our note on the Strait of Hormuz. It is the same energy shock that keeps US inflation elevated and US yields high, so it pushes the differential and the import bill in the same direction. One shock, both channels, both against the yen.

This is the part of the picture that did not improve on 3 September, and it is why the currency's recovery rests entirely on the policy leg.

What to watch next

• Friday's payroll print, 8:30 a.m. Eastern. It moves the American end of the gap, which is now the end with room to move. See our preview.
• US CPI and PPI the following week. Waller conditioned his hold on continued disinflation, which makes these, not payrolls, the true hinge before 16 September.
• The Bank of Japan's 4 September turnover figure, which will show whether Thursday's Tokyo session carried an operation's footprint.
• The Ministry of Finance's quarterly intervention release, which allocates the ¥15.4trn to specific dates and settles whether August buying occurred.
• Brent. Every dollar on the barrel is a tax on the yen that no central bank meeting offsets.
• The trade-weighted yen index, not just the dollar rate — 72.72 on 2 September against a 73.99 post-intervention high. It separates a yen story from a dollar story.

For the standing framework behind all of this, see our explainer on what moves the Japanese yen, the live factor scores on the yen page and the dollar page, and how the meter is built.

Educational macro context only — not investment advice.