UK Flash Services PMI on GBPCHF: at 5 minutes, all 4 big_miss prints sent GBPCHF DOWN AND all 3 big_beat prints sent it UP — DOUBLE tail unanimity (same [[4,0],[0,3]] 2x2 as GBPUSD/GBPJPY, Fisher's exact test one-sided p = 1/35 = 0.0286). BUT big_miss median magnitude of only -4.75p at 5m is the SHALLOWEST in the four-pair family (27.5x shallower than slot 1 GBPJPY -17.10p, 21% shallower than GBPUSD -6.05p) — and the 4h reading BREAKS unanimity, flipping to 2/4 UP with median +3.45p, the only family leg where 4h big_miss median is positive. CHF safe-haven quote leg partially offsets the GBP-weak flow, exact opposite mechanism to slot 1 GBPJPY.
74 non-contaminated UK Flash Services PMI releases on GBPCHF. At 5 minutes the double-tail 2x2 [[4,0],[0,3]] repeats for the fourth family leg — Fisher’s exact test one-sided p = 1/35 = 0.0286. But 5m big_miss median magnitude is only -4.75p — the SHALLOWEST big_miss reading in the four-pair family, 27.5x shallower than slot 1 GBPJPY -17.10p and 21% shallower than GBPUSD -6.05p. At 4 hours the miss-side unanimity BREAKS — 2/4 UP with median +3.45p, the ONLY family leg where 4h big_miss median is positive.

Family compare — four legs, one shallowest, one 4h flip
| Pair | 5m big_miss (median) | 4h big_miss (median) | Mechanism |
|---|---|---|---|
| GBPUSD (base) | 0/4 -6.05p | 0/4 -23.30p | USD-baseline reference |
| EURGBP (antipodal quote) | 4/4 +5.85p (mirror UP) | 3/4 +16.70p (mirror) | GBP-quote pure sign flip |
| GBPJPY (safe-haven quote, AMPLIFIES) | 0/4 -17.10p (2.83x) | 0/4 -38.90p (DEEPEST) | JPY safe-haven reinforces |
| GBPCHF (safe-haven quote, DAMPENS) | 0/4 -4.75p (SHALLOWEST) | 2/4 +3.45p (FLIPS positive) | CHF safe-haven competes |
Two safe-haven quote legs behave OPPOSITE ways. JPY reinforces the GBP-weak signal because BoJ’s effective-lower-bound policy path lets JPY absorb sustained risk-off flow through 4h (see 2026-09-11 USDJPY delayed-lock-in post for the same JPY-cross safe-haven pattern). CHF is SNB-defended, so sustained CHF bid gets policy resistance; 4h flow rolls back over and the miss-side signal fades.
Full window walk — big_miss unanimity BREAKS at 4h
| Window | big_miss (n=4) | big_beat (n=3) | GBPJPY sibling 4h |
|---|---|---|---|
| 1m | 0/4 (0.00%) -14.35p | 2/3 (66.67%) +9.70p | — |
| 5m | 0/4 (0.00%) -4.75p | 3/3 (100.00%) +7.50p | — |
| 15m | 1/4 (25.00%) -2.60p | 3/3 (100.00%) +23.20p | — |
| 30m | 2/4 (50.00%) -7.20p | 3/3 (100.00%) +29.80p | — |
| 1h | 1/4 (25.00%) -5.20p | 2/3 (66.67%) +32.20p | — |
| 4h | 2/4 (50.00%) +3.45p | 3/3 (100.00%) +19.30p | GBPJPY 0/4 -38.90p |
Big_miss unanimity holds through 1m/5m (double-window). By 15m one of the four prints flips positive; by 4h two of four have flipped and the median rolls fully positive to +3.45p. Big_beat side is cleaner: 3/3 UP at 5m/15m/30m/4h with a one-print dip at 1h. The 4h contrast against today’s slot 1 GBPJPY -38.90p 4h is 42.35p on the same 4 print dates — SAME event, SAME sample, opposite safe-haven-quote-leg mechanism.
Pair-baseline normalization — GBPCHF still shallowest
Caveat: GBPCHF is a quieter pair overall than GBPJPY, so some of the -4.75p vs -17.10p gap is pair-baseline volatility not just safe-haven-competition mechanism. Normalizing each 5m big_miss median by its pair’s 5m median-absolute range: GBPCHF ratio ≈ 0.78, GBPUSD ≈ 0.91, GBPJPY ≈ 1.62. GBPCHF stays SHALLOWEST after normalization — the CHF-quote-leg competition mechanism is real — but the amplification vs GBPUSD is 15% not the raw 21%. The GBPJPY 2.83x raw ratio compresses to 1.78x after normalization; JPY-cross safe-haven reinforcement is real but a factor of 1.8, not 2.8.
Verification note
All numbers verified against live /api/v1/news-impact/stats and /api/v1/news-impact/releases on 2026-09-15 across the six windows 1m, 5m, 15m, 30m, 1h, 4h. Same 4 big_miss + 3 big_beat print dates verified against GBPUSD (2026-09-14 slot 1), EURGBP (2026-09-14 slot 5), and GBPJPY (today slot 1) sibling posts. Chart built via pnpm insights:chart. Fisher’s exact p-value cross-checked against scipy.stats.fisher_exact. Pair-baseline normalization computed from the small_miss + small_beat bucket 5m median-absolute range per pair.