exchangerate.devJapan confirmed that it bought yen in coordination with the US Treasury. The US funding currency has no official confirmation. A purchase funded in euros would lower EUR/JPY during execution, with dollar pairs linked through cross-rate repricing.
- Japan officially confirmed the coordinated yen purchase. No official US transaction disclosure has confirmed euro funding.
- Selling EUR to buy JPY puts the first direct pressure on EUR/JPY: the pair falls as the yen strengthens against the euro.
- The identity
EUR/JPY = EUR/USD × USD/JPYmeans the dollar pairs must reprice too, but it does not determine which one absorbs more of the move. - From the July 30 to August 3 daily fixes, EUR/JPY fell 3.35% and USD/JPY fell 3.84%, while EUR/USD rose 0.51%. The event produced broad yen strength, not a simple euro collapse.
What happened
USD/JPY touched 163.74 on July 30, near a four-decade yen low, then fell as far as 155.32 within three trading sessions. Japan's Ministry of Finance confirmed that it bought yen on July 31 in coordination with the US Treasury and said it would not hesitate to intervene jointly again.
Why selling euros changes the first pair that moves
A sale of EUR to buy JPY would first lower EUR/JPY. As the yen strengthened, one euro would buy fewer yen. The New York Fed explains that it executes Treasury-directed intervention as fiscal agent and that US foreign-exchange reserves are held in euros and yen.
EUR/JPY does not move independently. The three major pairs must satisfy EUR/JPY = EUR/USD × USD/JPY, and banks reprice them almost instantly. EUR/USD can fall, USD/JPY can fall, or both can move. The equation fixes the relationship among the rates, not which market absorbs the order.
The US Treasury has not published an explanation.
If the US does it again
| Possible operation | Clearest pressure | What remains uncertain |
|---|---|---|
| A small US euro-for-yen trade | EUR/JPY lower during execution | Whether EUR/USD or USD/JPY carries more of the adjustment |
| US euro sales plus large Japanese dollar sales | Both EUR/JPY and USD/JPY lower | The size and duration of the yen move |
| Repeated or larger US euro sales | More persistent EUR/JPY pressure; possible EUR/USD pressure | The percentage move, because other flows can offset intervention |
The most reliable directional statement is the narrow one: another euro-funded yen purchase directly pushes EUR/JPY lower while it is executed. A broader yen rally becomes more likely if Japan also sells dollars, the operation is large, or traders expect further intervention. Persistence still depends on the forces that weakened the yen in the first place, including interest-rate differences, positioning, and energy-import costs. This is a map of the transmission, not an exchange-rate forecast.
What the data shows
Between the July 30 and August 3 ECB daily fixes, EUR/JPY fell from 186.99 to 180.73 (-3.35%) and USD/JPY fell from 162.94 to 156.68 (-3.84%). EUR/USD moved the other way, rising from 1.1476 to 1.1535 (+0.51%). The yen strengthened against both currencies, but the euro did not weaken against the dollar over the full window. Japan's activity, position-closing, and expectations of another intervention all sit inside those moves, so the daily observations cannot assign a separate effect to each cause.
The episode also shows the limit of daily FX data. The ECB series recorded USD/JPY at 162.94 on July 30, 160.235 on July 31, and 156.68 on August 3. It contains neither the 163.74 high nor the 155.32 low. Daily reference rates work for accounting and historical analysis; an alert or current-rate display needs an intraday source with timestamps and session context. The live USD/JPY page carries source, market_session, and data_updated_at on every observation.
Selling euros to buy yen tells you which cross receives the order. It does not, by itself, tell you where EUR/USD or USD/JPY will finish.