UK Core CPI on GBPJPY: 13 of 15 big-beat prints sent GBPJPY up at 15m (86.7%) — and at 5 minutes the big-beat bucket is 15 of 15 UP (100%). First-ever GBPJPY × UK Core CPI anchor, sixth cross-family leg with 5m unanimity.
198 non-contaminated UK Core CPI y/y releases (2010-01-19 through 2026-06-17) on GBPJPY. At 5 minutes: 15 of 15 big-beat prints sent GBPJPY UP (100% unanimous), coin-flip null p = 0.003%. At 15 minutes: 13/15 big-beat up (86.7%). Big-beat median walk +16.2 / +22.2 / +17.6 / +32.5 / +24.7 / +28.9p across 1m / 5m / 15m / 30m / 1h / 4h — persists through 4 hours.
First-ever GBPJPY × UK Core CPI News Impact anchor, and the sixth leg of the UK Core CPI cross-family after GBPUSD (2026-08-12), EURGBP (2026-08-20), GBPNZD (2026-08-27), GBPAUD (2026-08-29), and GBPCAD (2026-09-01). Only GBPCHF remains to close the full 7-pair GBP-cross family.

The full 5-bucket table at 15 minutes
| Bucket | n | Median | Pct-up | Interpretation |
|---|---|---|---|---|
| big_miss | 15 | -12.6p | 40.0% | 9 of 15 down; small_miss > big_miss bucket-boundary artefact |
| small_miss | 53 | -18.0p | 13.2% | GBP weak → GBPJPY down (46 of 53) |
| in_line | 62 | +3.9p | 56.5% | coin-flip |
| small_beat | 53 | +6.7p | 66.0% | GBP strong → GBPJPY up (35 of 53) |
| big_beat | 15 | +17.6p | 86.7% | GBP very strong → GBPJPY up (13 of 15) |
Beat side is the clean read: monotonic on both median (+6.7p → +17.6p) and pct-up (66.0% → 86.7%) from small_beat to big_beat. The miss side has a bucket-boundary artefact: small_miss (-18.0p, 13.2% up = 86.8% down) is BIGGER-magnitude and more consistently down at 15m than big_miss (-12.6p, 40.0% up = 60% down) because 6 of the 15 big-miss prints are boundary-z misses whose 15-minute walk drifted positive by the 15m mark. At 5m the pattern is cleaner: big_miss is 13/15 DOWN (86.7%). This is the SAME small_miss > big_miss pattern documented on US Core CPI × AUDUSD (2026-08-23) and US Core CPI × USDJPY (2026-08-31). Three independent event × pair replications make it a real bucket-cutoff artefact, not a one-pair fluke.
The 5-minute 15-of-15 big-beat unanimity
Every one of the n=15 big-beat prints since 2010-01-19 sent GBPJPY UP at 5 minutes. Under a coin-flip null of P(up) = 0.5, probability = 1/215 = 0.003%. Below, all 15 prints, sorted by date, with the 5m and 15m move in pips.
| Release date | surprise_z | 5m pips | 15m pips | 15m dir |
|---|---|---|---|---|
| 2010-01-19 | +2.59 | +40.0 | +23.0 | ↑ |
| 2010-07-13 | +2.18 | +29.0 | +36.0 | ↑ |
| 2012-08-14 | +1.94 | +8.9 | +1.9 | ↑ |
| 2012-11-13 | +3.51 | +9.0 | +6.6 | ↑ |
| 2014-07-15 | +1.68 | +54.9 | +61.9 | ↑ |
| 2015-08-18 | +3.16 | +74.3 | +100.0 | ↑ |
| 2017-03-21 | +1.92 | +34.5 | +33.5 | ↑ |
| 2017-06-13 | +1.99 | +8.4 | -12.4 | ↓ |
| 2018-09-19 | +2.58 | +56.0 | +46.0 | ↑ |
| 2020-08-19 | +3.08 | +5.2 | +8.0 | ↑ |
| 2021-06-16 | +1.95 | +12.9 | +6.9 | ↑ |
| 2022-04-13 | +1.98 | +9.7 | +17.6 | ↑ |
| 2022-08-17 | +1.54 | +22.2 | +9.6 | ↑ |
| 2023-03-22 | +2.32 | +15.0 | -8.2 | ↓ |
| 2023-05-24 | +2.59 | +38.2 | +26.7 | ↑ |
Two of the 15 flipped negative at 15 minutes: 2017-06-13 (UK hung-parliament week 2017-06-08 election, GBP-idiosyncratic-selling dominated the CPI signal — also the one negative-at-15m print for GBPCAD; +8.4p at 5m → -12.4p at 15m) and 2023-03-22 (BoE-decision week; +15.0p at 5m → -8.2p at 15m). Both were positive at 5 minutes. The 5-minute window is the tightest, cleanest read of the surprise signal on this pair.
Beat-side persistence through 4 hours
| Window | big_miss med | big_miss pct_up | big_beat med | big_beat pct_up |
|---|---|---|---|---|
| 1m | -15.9p | 26.7% | +16.2p | 93.3% |
| 5m | -10.9p | 13.3% | +22.2p | 100.0% |
| 15m | -12.6p | 40.0% | +17.6p | 86.7% |
| 30m | -7.2p | 33.3% | +32.5p | 86.7% |
| 1h | -4.1p | 46.7% | +24.7p | 93.3% |
| 4h | -8.9p | 30.8% | +28.9p | 80.0% |
The 5-minute row is the double-tail highlight: 15/15 big-beat up (100%) with median +22.2p. The beat-side median AMPLIFIES to +32.5p at 30m and holds +24.7p at 1h and +28.9p at 4h. Pct-up stays at 86.7% or higher at every window from 1m through 1h. The miss side is bucket-boundary-artefact-affected: median moves from -15.9p at 1m to -4.1p at 1h, driven by 2 of 15 prints that flipped positive.
Sixth leg of the UK Core CPI cross-family
| Pair | Post date | 15m big-beat pct_up | 5m big-beat pct_up | Unanimity window(s) |
|---|---|---|---|---|
| GBPUSD | 2026-08-12 | 86.7% | — | — |
| EURGBP | 2026-08-20 | 86.7% down (mirror) | — | — |
| GBPNZD | 2026-08-27 | 86.7% | 100.0% | 5m AND 1h (double) |
| GBPAUD | 2026-08-29 | 93.3% | 100.0% | 5m AND 30m (double) |
| GBPCAD | 2026-09-01 | 86.7% | 100.0% | 5m (single) |
| GBPJPY | 2026-09-02 | 86.7% | 100.0% | 5m (single) |
Every leg of the family posts 86.7-93.3% big-beat up at 15 minutes on the same 15-of-15 print membership. Four of the six pairs (GBPNZD, GBPAUD, GBPCAD, GBPJPY) now share 100.0% big-beat up at 5 minutes — 4 independent replications of the 15/15 unanimity on identical release dates. Only GBPCHF remains to close the 7-pair family; GBPJPY is now the loudest-pair beat-side amplitude in the family (+32.5p median at 30m, beating GBPAUD’s +23p and GBPCAD’s +24.5p).
Verification note
All numbers verified against live /api/v1/news-impact/stats and /api/v1/news-impact/releases on 2026-09-02 across all 6 windows. Chart generated via the standard pnpm insights:chartCLI. Sample: 198 non-contaminated UK Core CPI y/y releases 2010-01-19 through 2026-06-17 (last release June 2026 print). First-ever GBPJPY × UK Core CPI News Impact anchor. Big-miss and big-beat n=15 are below the MIN_N=30 chart threshold and drawn faint; the 5m 15/15 unanimity still clears p < 0.001 under coin-flip null even at n=15.