Scan: Will CPI rise more than 0.6% in September 2026? — Above 0.6%

1. Planner Fable 5.1 · Fermi decomposition + tool plan

Tools chosen: kalshi_direct kalshi_related polymarket_related fred resolution_source claude_news article_search code_execution

Sub-questions (Fermi decomposition)

What is the current Kalshi YES price for the >0.6% strike and what does the full KXCPI-26SEP strike ladder imply for the distribution of the September 2026 CPI m/m print?
What were the headline CPI-U seasonally adjusted month-over-month changes for the last 6-12 months through August 2026, and is there an upward trend?
What do the Cleveland Fed Inflation Nowcast and the economist consensus (Bloomberg/Reuters/WSJ survey) forecast for September 2026 headline CPI m/m?
How much did retail gasoline and broader energy prices change in September 2026 versus August 2026, and how large a contribution would that make to headline CPI?
Are there identifiable one-off or policy drivers in September 2026 (new tariffs, food price shocks, shelter/OER acceleration, hurricane effects) that could push headline CPI toward 0.7% or higher?
What is the historical base rate of headline CPI m/m prints exceeding 0.6% (rounded to one decimal), and how often does the print exceed the consensus by 0.2pp or more?
Is the September 2026 CPI release scheduled for release on or before the market close (Oct 14, 2026), and is there any government shutdown or BLS disruption risk?

Planner reasoning

A monthly headline CPI print above 0.6% is historically rare (only a handful of months since the 1980s, mostly energy-shock driven), so the question hinges on whether September 2026 has an unusual driver like a gasoline spike, tariff pass-through, or a nowcast/consensus already pointing near 0.6%. Key anchors are the Kalshi strike ladder, the Cleveland Fed nowcast and economist consensus, recent monthly CPI momentum, and September energy price moves. The market resolves on the BLS release, so its scheduled date and any shutdown-related delays also matter.

2. Research Parallel tool calls

tool	status	time	items	summary
kalshi_direct	OK	0.2s	1	## This Market's Kalshi Data Above 0.6% (KXCPI-26SEP-T0.6) - Current price (probability): 21.00% - 7-day price change: -4.00% - 30-day price change: +11.00% - Average daily volume: 2190 contracts - Price range: 2.00% - 38.00% - Data points: 34 days
kalshi_related	OK	8.5s	2	2 related markets / summaries. series KXCPI: 0 markets (skipped 44 no-signal) \| series KXCPICORE: 0 markets (skipped 44 no-signal) \| series KXCPIYOY: 0 markets (skipped 63 no-signal) \| keyword 'CPI September 2026': ok \| keyword 'inflation September': ok
polymarket_related	OK	0.7s	15	Polymarket search over 3 keyword(s), kept 15 matches. keyword 'CPI September': 5 markets \| keyword 'inflation September 2026': 5 markets \| keyword 'CPI': 5 markets
fred	OK	2.9s	6	Fetched 6 FRED series (lookback=400d).
resolution_source	OK	6.8s	1	already_resolved=no; matches_criteria=True; last_updated=September 11, 2026 (release covering August 2026 data). The most recent CPI data available is for August 2026, showing CPI-U increased 0.4% seasonally adjusted (3.4% over 12 months, NSA). The September 2026 CPI data has not yet been released;
claude_news	OK	31.2s	11	Key findings for September 2026 CPI (release due Oct 14, 2026): - No shutdown risk to release schedule: A government shutdown was averted — Trump signed a stopgap spending bill into law on September 2, 2026, funding the federal government at current levels through December 11 and averting
article_search	OK	47.2s	25	Fetched 25 unique articles across 5 queries (lookback=45d). 'September 2026 CPI forecast consensus': 10 articles \| 'Cleveland Fed inflation nowcast September 2026': 10 articles \| 'gasoline prices September 2026': 10 articles \| 'August 2026 CPI report inflation': 10 articles \| 'tariffs inflation pass
code_execution	OK	22.3s	0	## Key Findings - Historical base rate (unconditional): Using an approximate empirical distribution of headline CPI-U SA m/m prints from 1990–2025 (~430 months), roughly ~8% of months have printed ≥0.7% (i.e., "rise more than 0.6%"). This reflects that most months cluster in the 0.1–0.4% ra

3. Evidence Brief Sonnet 5 · 5832 chars

# Event Will September 2026 headline CPI (seasonally adjusted, single-decimal) print more than 0.6% month-over-month? (Kalshi: KXCPI-26SEP-T0.6) # Outcomes to forecast Yes (>0.6% m/m) / No (≤0.6% m/m) # Kalshi market anchor **YES = 21%** currently. 7-day change: -4pp (pullback from a recent high). 30-day change: +11pp (roughly doubled over the month, tracking the gasoline/oil spike narrative). Range over 34 days: 2%–38%. Avg daily volume ~2,190 contracts — this is a liquid, actively-traded market with real information content, and it has been drifting UP as the Iran-war fuel crisis intensified, then pulling back slightly as oil eased off its early-Sept peak. # Resolution source BLS (bls.gov/cpi, schedule page, cpi.nr0.htm). Last updated Sep 11, 2026, covering August 2026 data (+0.4% SA m/m, 3.4% YoY NSA). September 2026 data not yet published; scheduled release Oct 14, 2026, 8:30am ET — same day as market close (12:25 UTC), so release will occur before close. Resolution condition not yet met. # Sub-question answers 1. **Kalshi YES/ladder** — YES=21% for >0.6%. Full KXCPI ladder could not be retrieved (keyword searches returned no other strike rungs), so the implied full distribution is unknown beyond this single data point. [kalshi_direct/kalshi_related] 2. **Recent CPI trend (FRED CPIAUCSL, SA)** — Approx m/m: Nov25 +0.3%, Dec25 +0.3%, Jan26 +0.2%, Feb26 +0.3%, **Mar26 +0.9%**, **Apr26 +0.6%**, May26 +0.5%, Jun26 ~-0.1 to -0.4%, Jul26 +0.1%, Aug26 +0.4%. Volatile, not monotonic, but two recent months (Mar/Apr) already breached the 0.6% threshold amid tariff/energy shocks. [FRED] 3. **Nowcasts/consensus** — Cleveland Fed Nowcast: YoY easing to ~3.3% for Sept (from 3.38% Aug); Nowflation consensus YoY 3.7%. No explicit Sept m/m consensus published; back-solving from YoY forecasts implies m/m roughly 0.15%–0.55%, below the 0.6% threshold as base case. [claude_news] 4. **Gasoline/energy** — August CPI energy +2.1% (gasoline +3.9%), >1/3 of headline gain. Retail gas rose further in Sept: $4.08 (Aug 5) → $4.43 (Sept 17), +8.6%; WTI jumped from ~$87 (Aug 31) to $107 (Sept 15), +23%; diesel hit record ~$6/gal. September energy contribution to headline could exceed August's. [claude_news, FRED DCOILWTICO/GASREGW] 5. **One-off drivers** — 2026 Iran war fuel crisis (Strait of Hormuz disruption) is the dominant shock; tariff pass-through raising petroleum-based goods costs and shipping/logistics costs; shelter/OER remains largest core contributor but not specifically accelerating. These are genuine upside risks toward 0.7%+. [claude_news/article_search] 6. **Base rate** — ~8% of months (1990–2025) print ≥0.7% unconditionally. Conditional on a ~0.3–0.5% consensus, model-implied P(≥0.7%) ≈ 0.2%–11%, rising sharply with consensus level and forecast-error volatility (elevated now due to energy shock). [code_execution] 7. **Release timing/shutdown risk** — Release scheduled Oct 14, 2026, before market close; a Sept 2, 2026 stopgap bill averted a shutdown, funding government through Dec 11, removing near-term BLS disruption risk. [claude_news] # Key facts (high-confidence, factual) 1. [BLS] August 2026 CPI +0.4% SA m/m, 3.4% YoY NSA; gasoline +3.9%, energy +2.1%. 2. [FRED] March 2026 m/m ~+0.9%, April 2026 ~+0.6% — both exceed/meet the current threshold, showing 2026 has already seen high-volatility months. 3. [claude_news] Retail gasoline rose from $4.08→$4.43/gal between Aug 5–Sept 17, 2026; WTI crude rose from $87→$107/bbl over similar window. 4. [claude_news] Government shutdown averted via Sept 2, 2026 stopgap bill; BLS Sept CPI release on track for Oct 14. 5. [kalshi_direct] Kalshi YES price for >0.6% is 21%, up 11pp over 30 days, down 4pp over 7 days. # Cross-market signals - Kalshi related: Only long-horizon CPI-year markets found (2034-36), not directly comparable. - Polymarket: No direct September headline CPI m/m market found; Core CPI YoY markets imply YoY ~2.3–2.5% most likely (2.4% at 43.5%), consistent with continued core disinflation — tension with headline upside risk from energy. - Sportsbook implied: N/A. # Analyst opinions and speculation - BofA (Juneau): expects "limited inflation progress," supportive of continued Fed hikes given sticky inflation. - Natixis (Hodge): hotter-than-consensus CPI would push Fed toward hikes; broader narrative treats inflation as still elevated/risk-skewed upward due to Middle East conflict and tariffs. - Fed's own Nowcast (Cleveland Fed) sees core PCE reaccelerating even as headline YoY cools — mixed signal. # Directional lean per outcome - **Yes (>0.6%)**: Supported by sharp Sept gasoline/oil price surge (Iran war fuel crisis), diesel at record highs, tariff pass-through, and precedent of 0.6-0.9% prints earlier in 2026. Kalshi at 21% and rising 30-day suggests market sees this as a live, above-base-rate risk. - **No (≤0.6%)**: Supported by YoY consensus (3.3–3.7%) implying moderate m/m (~0.15–0.55%), recent Jun-Aug prints moderating to 0.1–0.4%, and historical base rate (~8% unconditional, lower when consensus is sub-0.5%) still below 50%. Kalshi's own 21% YES implies ~79% No. # Gaps / unknowns - No full Kalshi KXCPI strike ladder retrieved — can't cross-check implied distribution shape. - No explicit Wall Street Sept 2026 headline CPI m/m point-forecast found (only YoY figures); m/m estimate here is back-solved/approximate. - Exact gasoline CPI weight and pass-through magnitude for September not directly modeled; energy index revisions possible. # Calibration anchors - Kalshi current YES price: **21%** (anchor). - Empirical base rate for CPI m/m ≥0.7%: ~8% historically; conditional model estimate 2–11% given typical consensus levels, but 2026's realized volatility (two 0.6-0.9% prints already) argues for a higher-than-typical risk premium, roughly consistent with Kalshi's 21%.

4. Forecasters 5 draws · Fable 5.1 + GPT-5.6 Sol

claude-fable-5-1

50% conf

Yes	24%
No	76%

Kalshi prices YES at 21% in a liquid market that has doubled over the month on the Iran-war fuel shock, so the energy narrative is already largely priced. A rough Fermi build (core ~0.3% × 0.79 weight, food ~0.3% × 0.13, gasoline up ~8% SA × 3.3% weight plus other energy) lands headline around 0.5–0.6%, meaning a 0.7%+ print requires either a larger-than-modeled gasoline pass-through or a hot core/food surprise; nowcast-implied YoY (3.3–3.7%) back-solves to ~0.15–0.55% m/m. 2026 has already produced 0.9% and 0.6% prints, and forecast-error volatility is elevated, which justifies a risk premium above the ~8% unconditional base rate. I nudge slightly above the market to 24% because the September gasoline rise (~+8.6% retail, record diesel) roughly doubles August's energy impulse and September seasonal factors typically boost SA gasoline, leaving the threshold within one standard forecast error.

claude-fable-5-1

47% conf

Yes	23%
No	77%

Kalshi prices YES at 21%, and the brief gives no strong reason to move far from that. The Iran-war fuel shock is real: retail gasoline rose ~8.6% between early Aug and mid-Sept and WTI +23%, so a monthly-average gasoline gain of ~6-8% (boosted by September seasonal factors that normally expect falling gas prices) could contribute ~0.3pp alone, and combined with ~0.25pp core and food puts headline plausibly in the 0.5-0.7% range. However, back-solved consensus (YoY 3.3-3.7%) implies m/m ~0.15-0.55%, recent Jun-Aug prints moderated to 0.1-0.4%, core disinflation continues per Polymarket, and rounding to a single decimal means the print must reach ≥0.7% — a tail that historically occurs ~8% of months unconditionally. I nudge slightly above the market to 23% given the energy arithmetic and 2026's demonstrated volatility (0.9% and 0.6% prints in Mar/Apr), but the base case remains a 0.4-0.6% print.

claude-fable-5-1

45% conf

Yes	23%
No	77%

Kalshi prices YES at 21%, which is a liquid, actively-traded anchor that has already been drifting up on the Iran-war fuel shock. The September gasoline surge (retail +8.6% Aug–Sept, WTI +23%) with ~3.5% CPI weight plausibly adds 0.2–0.3pp on top of ~0.3% core/food, putting a 0.5–0.6% print in play but making >0.6% a tail rather than base case; the Cleveland Fed nowcast (YoY easing to ~3.3%) and back-solved m/m of 0.15–0.55% point to No. The 2026 precedent of 0.9% (Mar) and 0.6% (Apr) prints and elevated forecast-error volatility justify a modest premium over the ~8% unconditional base rate, roughly where the market sits. I nudge slightly above the anchor given unfavorable seasonal factors for gasoline in September (SA gasoline tends to run hotter than NSA) and record diesel pass-through.

gpt-5.6-sol

68% conf

Yes	21%
No	79%

I anchor on Kalshi’s liquid 21% YES price, which has already risen substantially as the Iran-war fuel shock intensified. September’s 8.6% retail-gasoline rise and 23% WTI surge create meaningful upside risk, especially after energy drove over one-third of August’s 0.4% CPI increase and 2026 already produced unusually hot monthly prints. However, available nowcasts imply roughly 0.15%–0.55% month-over-month inflation, recent underlying readings have generally moderated, and ≥0.7% prints have only an approximately 8% historical base rate. With no explicit September monthly consensus or precise model of energy pass-through, the evidence does not justify moving materially away from the market anchor.

gpt-5.6-sol

69% conf

Yes	22%
No	78%

Kalshi’s liquid-market anchor is 21% YES, already substantially above the roughly 8% historical base rate and therefore likely pricing the Iran-war energy shock. September gasoline rose about 8.6% and WTI about 23% through mid-month, while earlier 2026 prints of 0.9% and 0.6% demonstrate elevated volatility and support a small upward adjustment to 22%. However, available nowcasts imply only about 0.15%–0.55% month-over-month, recent June–August inflation was more moderate, and core disinflation limits the likelihood of the required 0.7%-or-higher rounded print. The scheduled BLS release appears unlikely to face disruption, so resolution-source uncertainty is minimal.

6. Final plain mean of 5 draws

23% (56% confidence)

Yes: 23% No: 77%

Mean of 5 draws (0.24, 0.23, 0.23, 0.21, 0.22). Kalshi prices YES at 21% in a liquid market that has doubled over the month on the Iran-war fuel shock, so the energy narrative is already largely priced. A rough Fermi build (core ~0.3% × 0.79 weight, food ~0.3% × 0.13, gasoline up ~8% SA × 3.3% weight plus other energy) lands headline around 0.5–0.6%, meaning a 0.7%+ print requires either a larger-than-modeled gasoline pass-through or a hot core/food surprise; nowcast-implied YoY (3.3–3.7%) back-solves to ~0.15–0.55% m/m. 2026 has already produced 0.9% and 0.6% prints, and forecast-error volatility is elevated, which justifies a risk premium above the ~8% unconditional base rate. I nudge slightly above the market to 24% because the September gasoline rise (~+8.6% retail, record diesel) roughly doubles August's energy impulse and September seasonal factors typically boost SA gasoline, leaving the threshold within one standard forecast error.

Pipeline Timing

Total pipeline time: 158.0s

Per-tool research timings shown in the Research section above.