RVRS AI Labs · research · official data through 2026-10-28
45 official yen-buying days since 1991, from the Ministry of Finance record. For the 13 days with minute data (2022, 2024, 2026), the path from six hours before to six days after.
Each line is one intervention: % change from the level just before it, every 30 minutes. The red line is the median of the lines shown.
shown n=13
Timing
All official yen-buying days, n=45. Dark: days with minute data.
Day move = median change of the Fed noon New York fix on the intervention day vs the day before. Thursday and Friday carry most of the 2022–2026 days, but the counts are small.
Days with minute data, n=13. Solid: time reported by the press. Hollow: time inferred from the price.
Tokyo hoursLondon / New York
An episode = interventions no more than 7 calendar days apart. 20 episodes.
24 years without a single yen-buying day separate 1998 and 2022. Recent episodes:
| Episode | Days | Span | Total | USD (est.) |
|---|---|---|---|---|
| 2022-09-22 | 1 | 0 d | ¥2.84 tn | $20.0 bn |
| 2022-10-21 → 2022-10-24 | 2 | 3 d | ¥6.35 tn | $43.3 bn |
| 2024-04-29 → 2024-05-01 | 2 | 2 d | ¥9.79 tn | $62.3 bn |
| 2024-07-11 → 2024-07-12 | 2 | 1 d | ¥5.53 tn | $35.0 bn |
| 2026-04-30 → 2026-05-06 | 3 | 6 d | ¥11.73 tn | $74.9 bn |
| 2026-07-30 → 2026-08-03 | 3 | 4 d | ¥15.40 tn | $96.8 bn |
After the hit
% and yen change from the pre-intervention level. Calendar hours; over a weekend the Friday close is carried. Days with minute data only.
| Horizon | Median | Median ¥ | Range | Below pre-level | First of episode | Follow-ups | Given back |
|---|---|---|---|---|---|---|---|
| Low within 6 h (43 min) | −2.79% | −¥4.19 | −3.81% … −0.98% | 13/13 | −3.16% n=6 | −1.69% n=7 | 0% |
| +1 h | −1.08% | −¥1.71 | −2.74% … −0.40% | 13/13 | −2.05% | −0.76% | 29% |
| +4 h | −1.17% | −¥1.85 | −2.80% … −0.18% | 13/13 | −2.38% | −0.76% | 39% |
| +8 h 1w | −1.10% | −¥1.73 | −2.64% … −0.07% | 13/13 | −2.31% | −0.77% | 33% |
| +12 h 2w | −1.32% | −¥2.08 | −2.64% … −0.12% | 13/13 | −2.13% | −0.80% | 43% |
| +24 h 3w | −1.77% | −¥2.83 | −2.72% … −0.01% | 13/13 | −2.20% | −0.80% | 33% |
| +2 days 7w | −1.74% | −¥2.54 | −3.38% … +0.39% | 12/13 | −2.25% | −0.80% | 31% |
| +3 days 6w | −2.19% | −¥3.51 | −3.38% … −0.12% | 13/13 | −2.25% | −0.72% | 43% |
| +4 days 2w | −2.18% | −¥3.46 | −4.13% … +0.39% | 12/13 | −2.34% | −0.72% | 41% |
| +5 days 4w | −1.82% | −¥2.93 | −4.14% … −0.05% | 13/13 | −2.67% | −1.49% | 36% |
| +6 days 4w | −1.78% | −¥2.83 | −4.14% … −0.05% | 13/13 | −3.21% | −1.49% | 49% |
Range = smallest to largest of the n=13 events. "w" = number of events whose horizon fell in the weekend close. Given back = median share of the drop (pre-level to running low) recovered by then: 0% is still at the low, 100% is fully back.
Amount spent vs move
MoF amount (¥ trillion) against the drop to the low and the move six days later. Spearman rank correlation with a permutation p-value; p-values are optimistic because events cluster in episodes.
Read with care: n = 13 from 6 episodes. The size of the first drop and the six-day move both lean toward bigger amounts, but one episode can carry the pattern.
Every event with minute data
¥2.84 tn · ≈$20.0 bn
2022-09-22 16:37 JST · 03:37 EDT
Tokyo close / London open · Time: high confidence
¥5.62 tn · ≈$38.4 bn
2022-10-21 23:36 JST · 10:36 EDT
London/NY overlap · Time: medium confidence
¥730 bn · ≈$4.9 bn
2022-10-24 08:33 JST · 19:33 EDT
Sydney/early Tokyo · Time: high confidence
¥5.92 tn · ≈$37.8 bn
2024-04-29 13:04 JST · 00:04 EDT
Tokyo (09:00-16:00 JST) · Time: medium confidence
¥3.87 tn · ≈$24.6 bn
2024-05-02 05:09 JST · 16:09 EDT
New York afternoon · Time: medium confidence
¥3.17 tn · ≈$20.0 bn
2024-07-11 21:25 JST · 08:25 EDT
London/NY overlap · Time: high confidence
¥2.37 tn · ≈$15.0 bn
2024-07-12 21:32 JST · 08:32 EDT
London/NY overlap · Time: medium confidence
¥6.28 tn · ≈$40.1 bn
2026-04-30 16:37 JST · 03:37 EDT
Tokyo close / London open · Time: medium confidence
¥780 bn · ≈$5.0 bn
2026-05-04 12:12 JST · 23:12 EDT
Tokyo (09:00-16:00 JST) · Time: low confidence
¥4.68 tn · ≈$29.9 bn
2026-05-06 13:18 JST · 00:18 EDT
Tokyo (09:00-16:00 JST) · Time: medium confidence
¥7.98 tn · ≈$50.0 bn
2026-07-30 22:00 JST · 09:00 EDT
London/NY overlap · Time: medium confidence
¥5.55 tn · ≈$34.9 bn
2026-07-31 16:44 JST · 03:44 EDT
Tokyo close / London open · Time: low confidence
¥1.87 tn · ≈$11.9 bn
2026-08-03 09:18 JST · 20:18 EDT
Tokyo (09:00-16:00 JST) · Time: low confidence
Time confidence: high = time reported by officials or several outlets; medium = reported by the press within a range; low = session from the press, minute inferred from the largest fall. Three events are low: 2026-05-04, 2026-07-31 and 2026-08-03.
1991–1998, daily data only
32 yen-buying days. No free minute data exists for them, so they use the Federal Reserve noon New York fix: the intervention day against the day before, then each business day after.
| Median move | d0 | d+1 | d+2 | d+3 | d+4 | d+5 | d+6 |
|---|---|---|---|---|---|---|---|
| 1991–1998 n=32 | +0.02% | −0.18% | −0.51% | −0.35% | −0.31% | −0.61% | −0.60% |
| 2022–2026 n=13 | −0.79% | −0.76% | −0.96% | −1.27% | −1.02% | −1.21% | −0.79% |
| Share below the day before, 1990s | 47% | 56% | 56% | 72% | 66% | 69% | 69% |
| Date | Weekday | Amount | d0 | d+6 |
|---|---|---|---|---|
| 1991-05-13 | Monday | ¥14 bn | +0.48% | −0.90% |
| 1991-06-10 | Monday | ¥21 bn | +1.13% | +0.42% |
| 1991-06-13 | Thursday | ¥21 bn | −0.40% | −2.04% |
| 1992-01-17 | Friday | ¥6.3 bn | −0.65% | −2.07% |
| 1992-02-17 | Monday | ¥13 bn | +0.06% | +1.37% |
| 1992-02-20 | Thursday | ¥77 bn | +0.20% | +0.58% |
| 1992-03-04 | Wednesday | ¥14 bn | +0.97% | +2.61% |
| 1992-03-11 | Wednesday | ¥25 bn | +0.43% | +0.29% |
| 1992-04-01 | Wednesday | ¥37 bn | +1.19% | −0.52% |
| 1992-04-27 | Monday | ¥74 bn | −1.04% | −1.08% |
| 1992-04-28 | Tuesday | ¥73 bn | +0.15% | −0.47% |
| 1992-04-30 | Thursday | ¥20 bn | −0.15% | −0.07% |
| 1992-05-22 | Friday | ¥52 bn | −0.65% | −2.09% |
| 1992-05-27 | Wednesday | ¥32 bn | +0.48% | −1.36% |
| 1992-05-28 | Thursday | ¥51 bn | −0.25% | −2.42% |
| 1992-05-29 | Friday | ¥32 bn | −1.44% | −1.87% |
| 1992-06-02 | Tuesday | ¥42 bn | +0.06% | +0.16% |
| 1992-06-03 | Wednesday | ¥31 bn | +0.21% | −0.61% |
| 1992-06-04 | Thursday | ¥18 bn | −0.18% | −0.90% |
| 1992-06-10 | Wednesday | ¥19 bn | +0.08% | −0.71% |
| 1992-06-18 | Thursday | ¥26 bn | −0.32% | −1.05% |
| 1992-06-25 | Thursday | ¥13 bn | −0.97% | −1.48% |
| 1992-07-24 | Friday | ¥29 bn | +0.82% | +0.51% |
| 1992-07-27 | Monday | ¥19 bn | +0.05% | −0.33% |
| 1992-08-07 | Friday | ¥13 bn | −0.20% | −1.57% |
| 1992-08-11 | Tuesday | ¥3.2 bn | 0.00% | −1.37% |
| 1997-12-17 | Wednesday | ¥280 bn | −2.96% | −0.44% |
| 1997-12-18 | Thursday | ¥76 bn | +1.21% | +2.40% |
| 1997-12-19 | Friday | ¥702 bn | +0.44% | +1.18% |
| 1998-04-09 | Thursday | ¥196 bn | −1.83% | −0.60% |
| 1998-04-10 | Friday | ¥2.62 tn | −0.96% | +1.55% |
| 1998-06-17 | Wednesday | ¥231 bn | −4.42% | −1.65% |
The 1990s were a different regime: much smaller amounts, often coordinated (1998-06-17 with the United States), and a noon fix cannot see the intraday spike.
Not in any figure above
Reported by the press but absent from the MoF record, so they are listed here and nowhere else. Press summaries are in English, with links.
Nikkei reported BOJ conducted a rate check with market participants (dollar was ~144.9 at the time per Jiji); seen as preparation for intervention.
rate check reported; MoF data shows no intervention that day (intervened 8 days later, 2022-09-22)
BOJ reportedly conducts FX rates check as yen plunges · Japan warns of intervention, BOJ conducts rate check amid yen fall
Yen hit 150.16 in NY then jumped ~2% in seconds after the 10:00 ET US JOLTS release. Officials declined to confirm or deny; BOJ money-market data next day suggested no intervention.
suspected, MoF data shows none (time inferred from JOLTS release; Japanese reports say 'night', Tokyo time)
Yen weakens past 150 per dollar as intervention concern mounts · Yen-tervention, was it or wasn't it? · ドル円は円高で149円付近|一時急落で市場介入の噂も
Nikkei (via MNI, 00:45 GMT Jul 12) reported BOJ rate-checking against the euro (EUR/JPY) the day after the CPI-day intervention. The Jul 11 and Jul 12 operations were both unannounced (stealth), confirmed later by MoF.
rate check reported; intervention also confirmed by MoF for this date (stealth)
MNI BRIEF: BOJ rate checking euro, may intervene · Japan Intervened into Forex Market July 11-12
Two episodes on Fri Jan 23: (1) late Tokyo, after BOJ hold and Ueda presser, USD/JPY dropped from >159 to <157.4 amid rumors of a BOJ rate check (Ueda declined to comment); (2) in NY session Reuters source said the New York Fed checked dollar/yen rates with dealers on behalf of Treasury (Fed minutes later confirmed desk asked for quotes).
rate check reported (NY Fed, later confirmed in Fed minutes per secondary source); BOJ money-market data indicated no Japanese intervention; MoF data shows none
Yen rises to more than two-month high as markets on alert for interven · Dollar Briefly Dives below 157.4 Yen in Tokyo · Fed rate check, US dollar and gold
Nikkei reported the NY Fed, on Treasury instruction, requested USD/JPY rate checks from several banks on Jul 30 (EUR/JPY on Jul 31), alongside Japan's unannounced intervention.
rate check reported (US); Japanese intervention confirmed later by MoF
Japan carries out yen-buying intervention as US executes rate check · Washington Can Support the Yen, But Not Break the Carry Trade
In NY trading Sep 3 speculation spread that Japanese authorities conducted a rate check; yen rose ~1 yen in a short time after breaking the 158 / 200-day MA area. Nikkei reportedly said officials conducted rate checks after the yen's sharp drop (not verified from primary).
rate check speculated, unconfirmed; MoF data shows no intervention (Q3 list only Jul 30, Jul 31, Aug 3; Aug 27-Sep 28 monthly total zero)
Yen rally (Sept 4 report) · Yen Surges on Suspected Rate Check · Japan currency intervention amounted to JPY 0 from August 27-Sep 28
Reports that the BOJ conducted a rate check with market participants 'late Friday' (the Friday before the Sep 21 holiday weekend; date inferred), after the yen fell >2% that week despite the BOJ hike to 1.25%.
rate check reported (secondary sources only, date inferred); MoF data shows none
Yen Consolidates Amid Holiday-Thinned Trading · BOJ conducted a rate check with market participants late Friday (Nikke
Yen slid to ~159.9 after hot US inflation / Fed hike bets; Mimura said moves were 'too fast' and markets should not forget the summer joint intervention. No rate check or intervention reported.
verbal warning only; no intervention reported as of 2026-11-12
Yen nears key ¥160 level after U.S. inflation data, sparking intervent · Yen Weakens to Over Two-Month Lows (news stream)
Methods, sources, limits
Every day in the Ministry of Finance record where Japan sold US dollars and bought yen: 45 days. Amounts are MoF's, in yen; the USD figure is our estimate at the Fed noon rate. MoF dates are trading-day dates.
The anchor (0 h) is the highest price from 30 minutes before to 10 minutes after the time reported by the press (10 of 13 events). For the other three it is the high that starts the largest 90-minute fall that day, which the reported session agrees with.
Minute data for 2022–2026. Moves are % and yen from the anchor; the low is the lowest point within 6 hours. Only these derived figures are published, never the underlying price feed. 1991–1998 use the Federal Reserve noon fix.
Record coverage: MoF daily record April 1991 - 2026-09-30 (quarterly release 2026-11-09); monthly release 2026-09-29..2026-10-28 = 0; 2026-10-29 onward not yet published
Not yet covered: 2026-10-29 → (next MoF monthly release, around the end of November 2026) · built 2026-11-12