Tools chosen: polymarket_direct polymarket_related kalshi_related claude_news claude_news fred gdelt_news wikipedia code_execution

Sub-questions (Fermi decomposition)

Planner reasoning

This is a Polymarket question on whether the BoE holds Bank Rate at its September 2026 MPC meeting. The primary anchor is the Polymarket price; secondary anchors are Kalshi's central-bank decision series and market pricing/OIS expectations for UK rates. Key drivers are UK inflation/labour data, the BoE's recent cut cadence (quarterly cuts pattern), and whether September is a 'live' meeting (historically the BoE has favoured acting at MPR meetings in Feb/May/Aug/Nov).

# Current state Bank Rate has been held at 3.75% since the December 2025 cut, through five consecutive 2026 meetings (Feb–Jul), with MPC dissent shifting from dovish (wanting cuts) early in the year to hawkish (wanting hikes) by mid-2026 amid Middle East-driven energy inflation. The September 17, 2026 decision is not yet made; markets and economists heavily favor another hold, but this is a forecast, not yet a resolved fact. # Timeline of key events - 2025-12: Bank Rate cut to 3.75% (confirmed, BoE). - 2026-02-04: Held at 3.75%, MPC voted 5–4 (4 wanted a cut to 3.5%) — dovish dissent (confirmed, BoE). - 2026-03: Held at 3.75%, unanimous vote; Middle East conflict cited as raising energy/commodity prices (confirmed, BoE). - 2026-04: Held at 3.75%, MPC voted 8–1 (1 wanted a hike to 4%) — dissent flips hawkish (confirmed, BoE). - 2026-06: Held at 3.75%, MPC voted 7–2 (2 wanted a hike); OIS curve briefly eased on a Middle East peace-deal announcement (confirmed, BoE). - 2026-07-30: Held at 3.75%, MPC voted 6–3 (3 wanted a hike to 4%) — dubbed a "hawkish hold" by analysts; Bailey did not signal imminent hike (confirmed, BoE/HOA). - 2026-08 (data for July): CPI rose to 2.9% (from 2.6%), first reacceleration since March 2026; services CPI 3.4% (down from 3.6% in June); wage growth 3.5% regular/4.1% total; unemployment rose to 5.0% (confirmed, ONS). - 2026-08-13/18: Economist survey (56/64, ~90%) expects hold through year-end; OIS pricing (as of 8/17) implies ~72–76% probability of hold at Sept 17 meeting, with residual skew toward a hike (+7bp implied move) (reported, HOA/centralbank.watch/bluegamma.io). - 2026-09-17: Scheduled MPC decision (pending — not yet occurred). # Event Will the Bank of England leave Bank Rate unchanged at its September 17, 2026 MPC meeting (relative to the pre-meeting level)? # Outcomes to forecast Yes (no change) / No (any change, up or down) # Kalshi market anchor No kalshi_direct data was returned for this ticker; the market data available under this exact ticker is from **Polymarket**: current YES ("No change") price = **92.5%**, 7-day change –0.5%, 30-day change +7.0% (price range 51.5–95.5% over 65 days), volume ~$101,560. This is treated as the primary consensus anchor in absence of a distinct Kalshi quote. Kalshi's own BoE-specific series (KXBOE) returned zero active markets. # Sub-question answers 1. **Polymarket YES price/trajectory** — 92.5% currently, up sharply from a 30-day low near 51.5–55%, and largely flat over the past week (Polymarket direct). 2. **Current Bank Rate & recent decisions** — 3.75% since Dec 2025; held at every 2026 meeting through July: Feb (5–4, dovish dissent), Mar (unanimous), Apr (8–1, hawkish dissent), Jun (7–2), Jul (6–3, "hawkish hold") (BoE minutes via claude_news). 3. **OIS/market-implied expectations** — OIS pricing as of mid-Aug 2026 implies ~72–76% probability of no change, with the residual probability skewed toward a hike (+7bp average implied move) rather than a cut (bluegamma.io, centralbank.watch). 4. **Historical base rate of no-change** — All-meeting hold rate ~51% (2021–2026 sample); non-MPR meetings (Mar/Jun/Sep/Dec, the September slot) show ~68% hold rate; September-only small sample (n=5) ~80% (code_execution analysis). September, as a non-forecast-round meeting, historically has an elevated hold propensity. 5. **Latest CPI/wages/unemployment** — CPI 2.9% (July 2026, up from 2.6%); services CPI 3.4% (down from 3.6% June); wage growth 3.5%/4.1% (regular/total); unemployment up to 5.0%; GDP growth weak (ONS/moneytothemasses). Inflation reacceleration and hawkish dissent argue against a September cut; weak growth/rising unemployment offers modest dovish counter-pressure, but not enough per survey/market data to flip the call toward a cut. 6. **Kalshi comparable market / disagreement with Polymarket** — No distinct Kalshi BoE September 2026 market found (KXBOE series empty); no cross-venue price disagreement observable from raw data. # Key facts (high-confidence) 1. [BoE] Bank Rate = 3.75%, unchanged since Dec 2025 through Jul 2026 (5 straight holds). 2. [BoE] Jul 2026 vote 6–3 hold, with dissent entirely hawkish (want hike to 4%). 3. [ONS] CPI 2.9% in July 2026, up from 2.6% — first reacceleration since March. 4. [HOA] ~90% of surveyed economists (13–18 Aug 2026) expect hold through year-end. 5. [bluegamma.io/centralbank.watch] OIS-implied hold probability 72–76%, residual risk skewed to a hike. # Cross-market signals - Kalshi related: no BoE-specific market found; unrelated Fed-funds/Atlanta Fed markets only. - Polymarket (this ticker): 92.5% YES for no-change — notably higher than OIS (72–76%) and economist-survey-implied consensus. - Sportsbook implied: n/a. # Analyst opinions and speculation - "Hawkish hold" framing (HOA, cambridgecurrencies) — growing internal support for a hike (2→3 dissenters) but Bailey signaling no urgency. - moneytothemasses flags weak GDP/rising unemployment as dovish counterweight, but this view is a minority framing versus the hold-consensus mainstream. - 2026 rate forecasts range 3.50–4.25%, with hold as base case but hike to 4.00% a live risk if services inflation stays elevated. # Directional lean per outcome - **Yes (no change)**: Strongly favored — 5 consecutive 2026 holds, ~90% economist consensus, 72–76% OIS-implied, 92.5% Polymarket price, ~68% non-MPR historical base rate. All signals point the same direction. - **No (change)**: Weak — if a change occurs, most evidence (hawkish MPC dissent, CPI reacceleration to 2.9%, OIS residual skew) suggests a hike is more likely than a cut, but overall change probability is low (~8–25% depending on source). # Gaps / unknowns - No direct Kalshi price for this exact contract in raw data — relying on Polymarket as anchor; true Kalshi consensus may differ. - August/September CPI, wage, and MPR data (which would directly precede the Sept 17 decision) not yet available in research. - Polymarket's 92.5% is notably more confident than OIS/survey figures (72–90%); the gap is unexplained and could reflect thin/late-mover liquidity or overconfidence. # Calibration anchors - Polymarket YES price (proxy anchor): 92.5%. - OIS-implied hold probability: 72–76%; economist survey: ~90%. - Historical base rate for non-MPR (September-slot) meetings: ~68%; September-only small-sample: ~80%.

1. Both forecasters converge tightly (0.88–0.90) without adequately explaining why they discount OIS (72–76%) so heavily in favor of Polymarket (92.5%)—the brief explicitly flags this ~15-20pt gap as "unexplained" and possibly due to "thin/late-mover liquidity," yet neither forecast seriously entertains that Polymarket could be the mispriced outlier rather than OIS. 2. Neither forecast grapples with the missing August/September CPI and wage data that will directly precede the meeting; the brief flags this as a key gap, and given the July reacceleration to 2.9% CPI with hawkish dissent trending (2→3 dissenters over three meetings), an extrapolation of that dissent trajectory could push the hike probability meaningfully higher than either forecaster's ~10-12% No allocation. 3. Both forecasters treat the "hawkish dissent momentum" (5-4 dovish → unanimous → 8-1 hawkish → 7-2 → 6-3) as a static tail risk rather than a trend; if dissent continues escalating (e.g., to 5-4 hawkish by September), a hike becomes far more plausible than the flat ~10% No probability implies, and neither forecast explicitly models this trajectory. 4. Neither critique addresses the specific asymmetry within the "No" outcome — both note "hike more likely than cut" but don't quantify it, leaving ambiguity about whether their ~10-12% No mass is split 90/10 hike/cut or something else, which matters for any sub-market on direction of change. 5. Both anchor heavily on Polymarket despite explicit brief caveats that this is a "proxy" anchor with no direct Kalshi quote and a suspiciously high 30-day run-up (from ~51.5% to 92.5%); neither forecaster discusses what might have driven that rally (e.g., a specific hawkish data point or event) or whether it's justified versus representing a herding/momentum effect. 6. The historical base-rate section notes September-only sample is small (n=5, ~80% hold rate) — both forecasters cite this as supportive but don't flag the sample-size fragility, potentially overstating its evidentiary weight relative to the more robust ~68% non-MPR rate.

89% (72% confidence)

Yes: 89% No: 11%

Five consecutive 2026 holds, ~90% economist consensus for a hold through year-end, the 92.5% Polymarket price on this exact contract, and an elevated ~68–80% historical hold rate for non-MPR September meetings all point the same direction. The main counterweight, correctly flagged by the critique, is meeting-dated OIS implying only ~72–76% hold with residual skew to a hike, plus an escalating hawkish dissent trajectory (8–1 → 7–2 → 6–3) and July CPI reaccelerating to 2.9% — so I shade below the Polymarket anchor rather than matching it. However, OIS a month out routinely carries residual risk premium that decays as data arrives, and the dovish offsets (unemployment at 5.0%, weak GDP, services CPI easing to 3.4%, Bailey signalling no urgency) make an immediate September hike unlikely; a 6–3 vote still needs two more converts. I land at 0.89 Yes, with the 11% No mass roughly 85/15 skewed toward a hike over a cut.

Total pipeline time: 171.8s