CPI month-over-month in Sep 2026? — Exactly 0.4%

- [2026-09-11] BLS released August 2026 CPI: the Consumer Price Index for All Urban Consumers (CPI-U) increased 0.4 percent on a seasonally adjusted basis in August after rising 0.1 percent in July, the U.S. Bureau of Labor Statistics reported today. This is the most recent official monthly reading available. https://www.bls.gov/news.release/archives/cpi_09112026.htm - [2026-09-11] CNBC confirmed the print: The consumer price index rose a seasonally adjusted 0.4% for the month, putting the 12-month increase at 3.4%, the Bureau of Labor Statistics reported Friday. Core CPI came in at 0.3% m/m. https://www.cnbc.com/2026/09/11/cpi-inflation-report-august-2026.html - [2026-09-11] The August release states the next report's timing: The Consumer Price Index news release for September 2026 is scheduled to be published on Wednesday, October 14, 2026, at 8:30 a.m. This is the resolution source for the question. https://www.bls.gov/news.release/archives/cpi_09112026.htm - [2026-09-22] Multiple independent trackers corroborate the same date: September 11, 2026 (August 2026 data); October 14, 2026 (September 2026 data); November 10, 2026 (October 2026 data); December 10, 2026 (November 2026 data). https://nowflation.com/cpi-release-dates - [2026-09-22] The October 14, 2026 release date falls on the market's trading-close day itself, meaning the actual September MoM figure will be published (at 8:30am ET) before the 2026-10-14 close, so the market should be able to resolve definitively on data rather than estimates. https://nowflation.com/cpi-release-dates - [2026-09-22] Nowflation's tracker only publishes year-over-year consensus/forecast figures for the upcoming September print (consensus 3.7% YoY, Nowflation's own model 3.55% YoY as of data as-of date 2026-09-22); no month-over-month consensus figure for September 2026 has yet been published by that tracker. https://nowflation.com/cpi-release-dates - [2026-09-23 (13 hours old per snippet)] TradingEconomics' prior-month characterization (referring to the August print, published ahead of the Sep 11 release) noted: The annual US inflation rate is expected to have held steady at 3.4% in August 2026, matching the July reading. On a monthly basis, CPI is forecast to rise 0.4%, the strongest increase in three months, following a 0.1% gain in July. That forecast for August (0.4%) matched the actual print; no equivalent September MoM forecast was found in current sources. - [2026-09-11] Kiplinger noted the context heading into the Fed's next decision: The August CPI report is the last inflation update the Fed will see before next week's policy meeting. This underscores that the September CPI print (due Oct 14) will be a fresh, market-moving data point but will arrive after the September FOMC meeting. https://www.kiplinger.com/investing/economy/cpi-report-august-2026-what-to-expect - [2026-09-11] CNBC quoted an economist reacting to the hot August core print, indicating recent momentum in inflation has been sticky/upside: "Chair Warsh and others signaled that interest rates can remain on hold only if disinflation continues and today's August report did not deliver that," said Kathy Bostjancic, chief economist at Nationwide. https://www.cnbc.com/2026/09/11/cpi-inflation-report-august-2026.html - [2026-09-23] Recent monthly headline prints for 2026 (per BLS/trackers): Jan–Jun readings driving YoY of 2.4%–4.2%, July +0.1% m/m, August +0.4% m/m — showing a volatile pattern with no single "typical" monthly value; 0.4% has occurred once (August) in the last several months of data currently available. https://www.bls.gov/news.release/archives/cpi_09112026.htm - [2026-09-22] No shutdown-related delay to the CPI schedule was found; the BLS calendar and third-party trackers (Nowflation, CalendarX, SmartCalendars) all consistently list October 14, 2026 as the September CPI release date. https://www.bls.gov/schedule/2026/10_sched_list.htm BOTTOM LINE: The September 2026 CPI report is officially scheduled for release on October 14, 2026 at 8:30am ET — the same day the market closes — so this question should resolve on the actual BLS print rather than remain unresolved; the most recent print (August 2026, +0.4% m/m) hit exactly the value in question, but no confirmed consensus specifically for the September MoM figure was located, so current data offers only indirect (base-rate) evidence rather than a market forecast for September itself. NOT FOUND: A specific Wall Street/consensus forecast for the September 2026 CPI month-over-month (as opposed to year-over-year) figure; any BLS schedule change or government-shutdown-related delay affecting the October 14, 2026 release; the Kalshi market's own current pricing/odds for this specific "exactly 0.4%" contract.

- [2026-09-11] The most recent official BLS release shows August 2026 headline CPI (seasonally adjusted) rose exactly 0.4% m/m, matching the market's target value, after a 0.1% rise in July 2026. The Consumer Price Index for All Urban Consumers (CPI-U) increased 0.4 percent on a seasonally adjusted basis in August after rising 0.1 percent in July, the U.S. Bureau of Labor Statistics reported. - [2026-09-11] BLS's own six-month trailing table shows monthly seasonally-adjusted headline changes for 2026 of: Feb 0.3%, Mar 0.9%, Apr 0.6%, May 0.5%, Jun -0.4%, Jul 0.1%, Aug 0.4% — only one of these seven prints (Aug) landed exactly at 0.4%, a roughly 14% historical hit-rate in this recent window (source: BLS Table A, cpi.htm). - [2026-09-11] BLS confirms the next release covering September 2026 data is scheduled for October 14, 2026 at 8:30am ET — the same date the Kalshi/related markets close. The Consumer Price Index news release for September 2026 is scheduled to be published on Wednesday, October 14, 2026, at 8:30 a.m. (ET). - [2026-09-22] Nowflation's tracker (which grades Street consensus against actual prints) reports that of the last 27 headline CPI releases, the Street consensus matched the print exactly 11 times (within 0.05 percentage points) — implying consensus is a moderately reliable but imperfect predictor of the exact one-decimal outcome, roughly a 40% exact-match base rate for forecasters generally (though this tracks YoY, not MoM, matches). - [2026-09-22] Nowflation's September 2026 CPI page (YoY-focused, published before the September data are in) still cites only a "consensus 3.7%" YoY figure with no MoM headline consensus yet published, indicating that a firm Wall Street MoM consensus for the September 2026 report was not available in the sources checked as of this writing. - [2026-09-18] Robinhood's prediction-market page for "CPI in September" (Oct 14, 2026 release) frames the contract as predicting the one-month percent change in the seasonally adjusted Consumer Price Index for All Urban Consumers (CPI-U) for Sep 2026, as reported by the U.S. Bureau of Labor Statistics (BLS) , confirming this is a standard recurring monthly-release market type rather than a one-off event. - [2025-09-XX to 2025-11-XX] Illustrating disruption risk to this reference class: the October 2025 CPI report was skipped entirely due to a government shutdown. Due to the lapse in appropriations, the BLS did not publish data for October 2025. As a result, the "month-over-month change" values for November 2025 show the change from September 2025 to November 2025. This shows the base-rate reference class (monthly CPI prints landing on any single value including 0.4%) can be disrupted by process/administrative risk, not just economic surprise. - [2026-09-22] The Robinhood contract's own rules explicitly account for this shutdown-type risk: In the case of a delay in data caused by a federal government shutdown impacting the reliability of the Source Agency, the market's latest Expiration Date will be extended to the sooner of the release of the Underlying or six months after the end of the government shutdown. - [2026-09-22] A model-based (non-consensus) long-range forecaster, Long Forecast, projects a small end-of-month CPI index rise for September 2026, implying a m/m change on the order of a few tenths of a percent (their metric is not the standard BLS m/m %, but points to modest, not sharp, m/m growth), consistent with sub-1% base case scenarios rather than an outlier print. CPI at the end 3.440%, change for September 0.080 points. - [2026-08-12] Historical July 2026 print of 0.1% m/m came in exactly in line with the Dow Jones consensus, per CNBC: The consumer price index...showed a seasonally adjusted increase of 0.1% during July, according to the Bureau of Labor Statistics...All of the readings were line with the Dow Jones consensus forecasts. This shows that in stable months, consensus/BLS matches are common, but the specific 0.4% value is just one of several plausible discrete monthly outcomes (range recently -0.4% to 0.9%). BOTTOM LINE: Over the last seven reported months (Feb–Aug 2026) headline seasonally-adjusted CPI m/m has hit exactly 0.4% only once (August 2026), implying a base-rate/outside-view probability in the rough 10–20% range for any single future month landing precisely on 0.4%, especially given recent volatility (readings from -0.4% to 0.9%) driven by tariff and energy effects; no firm September-specific MoM consensus was found yet to sharpen this further. NOT FOUND: A published Wall Street or FactSet consensus specifically for the September 2026 CPI month-over-month (headline) figure; a long-run (multi-year) frequency table of exact 0.4% m/m CPI prints; historical accuracy/track record of Kalshi-style prediction markets specifically on exact single-decimal CPI m/m outcomes.

- [2026-09-21] Gasoline kept climbing after the August print: AAA's national average hit $4.48 a gallon on September 21st, bringing it closer to this year's record high of $4.56 reached on May 21st , extending the same energy-driven inflation impulse that produced August's 0.4% print. https://tradingeconomics.com/commodity/gasoline - [2026-09-17] AAA reported a large single-week jump — the national average for a gallon of regular gasoline is up 16 cents from last week at $4.43 and more than one dollar higher than it was a year ago, with crude oil remaining high, averaging $100 per barrel amid continued volatility in the Strait of Hormuz — a mechanism directly analogous to the one that drove August's headline print. https://newsroom.aaa.com/2026/09/pump-prices-keep-climbing-as-crude-oil-remains-high-2/ - [2026-09-10] The prior week also showed a sharp gas-price jump: the national average for a gallon of regular gasoline went up 13 cents since last week to $4.27 as crude oil prices continue climbing, with volatility in the Strait of Hormuz pushing crude oil back in the $100 per barrel range for the first time since July , showing the run-up that will feed directly into the September CPI energy index. https://newsroom.aaa.com/2026/09/national-average-jumps-13-cents-in-one-week/ - [2026-09-04] Independent of AAA's weekly snapshots, a broader survey found as of September 4, drivers in the U.S. paid an average of $4.15 per gallon for regular gasoline, about 7 cents higher than the $4.08 national average recorded on August 5, representing a monthly increase of 1.6% — confirming energy was still rising into the September collection window, not falling as some bank models assumed. https://www.chooseenergy.com/data-center/cost-of-driving-by-state/ - [2026-08-11 (published)] The August BLS release itself shows how large the energy channel can be: the index for gasoline rose 3.9 percent in August, accounting for over one third of the monthly all items increase, while the index for energy increased 2.1 percent over the month — the same channel is still active heading into September given the AAA data above. https://www.bls.gov/news.release/cpi.htm - [2026-09 (Minneapolis Fed analysis)] Tariff pass-through into core goods has strengthened, not faded: through December 2025, the fitted line is flat, indicating little relationship between inflation in core goods categories and tariffs; by July 2026, however, that relationship has turned markedly positive, with both weighted and unweighted least squares lines showing positive coefficients , implying continued upward pressure on goods prices into September's print. https://www.minneapolisfed.org/article/2026/initially-delayed-the-pass-through-of-tariffs-to-consumer-prices-has-arrived - [2026-09] A companion Minneapolis Fed finding quantifies the size of this pressure: that category is adding on its own about 0.4 percentage points to core inflation, and so it's on the same order of magnitude as tariffs (referring to AI-driven goods inflation), indicating two separate upside forces (tariffs and AI-goods pricing) are simultaneously pushing core CPI, which could sustain a 0.4% headline if energy also contributes as it did in August. https://www.mprnews.org/story/2026/09/09/tariff-costs-are-being-passed-on-to-consumers - [revised 2026-09 NY Fed staff report] A freshly revised NY Fed paper confirms tariffs are still directly lifting consumer prices: studying the 2025 U.S. tariffs, researchers find that about 26 percent of the tariff increase passes through to consumer prices, measured relative to less-exposed goods and holding aggregate conditions fixed , a mechanism still working its way through the pipeline as of September. https://www.newyorkfed.org/research/staff_reports/sr1201 - [2026-08-18 St. Louis Fed] Even the more moderate St. Louis Fed read still shows tariffs adding to inflation, just at a steadier pace: combined with lower effective tariff rates, our estimates show that the effect of tariffs on inflation appears to have leveled off in the last few months or even declined slightly , but crucially the effect remains positive, not negative, consistent with a repeat 0.4% rather than a sharp deceleration. https://www.stlouisfed.org/on-the-economy/2026/aug/tariff-effects-inflation-stabilize-recent-months - [2026-08-23 pre-print market data] Ahead of the actual August release, prediction-market pricing on the related Kalshi CPI series showed real, non-trivial odds attached to strong upside outcomes: this market's price has trended upward from a 3.0% starting probability, trading within a range of 2.0% to a high of 30.0%, with a sharp 18.0 percentage point spike on August 22, 2026, which moved the price from 2.0% to its current level of 20.0% for an "Above 0.4%" threshold, indicating traders were already pricing meaningful probability mass at or above the 0.4% level even before August's print confirmed it. https://www.octagonai.co/markets/economics/inflation/cpi-in-september - [2026-09-11] Nationwide's chief economist framed the persistence risk explicitly in reaction to the August report, a dynamic still relevant for September: recent momentum has been "sticky," not disinflationary, per Kathy Bostjancic's comments cited by CNBC, reinforcing that another above-trend monthly print is plausible rather than a reversion to the more modest 0.1%–0.3% range seen earlier in 2026. https://www.cnbc.com/2026/09/11/cpi-inflation-report-august-2026.html - [2026-09-09] A Minneapolis Fed researcher summarized the compounding nature of current price pressures: "it could be that they don't feel the ability to pass through those price increases, so they're seeing lower profits… or it could be that they're substituting to different suppliers to avoid the tariffs" — the fact that firms are still adjusting supply chains in September (rather than having fully passed through costs already) suggests the tariff/AI-goods inflationary impulse is ongoing rather than a one-off spike confined to August. https://www.mprnews.org/story/2026/09/09/tariff-costs-are-being-passed-on-to-consumers BOTTOM LINE: The single most likely path to YES is a repeat of August's mechanism — a sharp, continuing gasoline/energy price increase (AAA data through Sept 21 show gas at/near 2026 highs) compounding with sticky core inflation from tariff pass-through and AI-driven goods pricing — reproducing another exactly-0.4% headline print; multiple Fed research threads (Minneapolis Fed, NY Fed, St. Louis Fed) confirm these forces remain active and positive, not reversing, into September. NOT FOUND: A confirmed, current (post-August-release) Wall Street consensus specifically for the September 2026 CPI headline month-over-month figure; the exact live-market implied probability for the specific "exactly 0.4%" Kalshi contract (only stale, pre-August-print bucket data was found); a September-specific Cleveland Fed CPI nowcast figure (site does not yet publicly display it).

**Strongest NO-case evidence** - [2026-09-22] EIA's weekly retail fuel survey shows US regular gasoline climbing sharply through September: nationally, regular gasoline averaged 4.478 dollars per gallon on September 21, 2026, up from 4.319 dollars on September 14 and 4.157 dollars on September 7 , a rise of roughly 7-8% within the month that will feed directly into the September energy CPI component and could push headline CPI above 0.4% rather than landing exactly on it. https://www.indexbox.io/blog/eia-weekly-fuel-price-update-us-gasoline-and-diesel-prices-rise-on-september-22-2026/ - [2026-09-22] TradingEconomics' gasoline tracker corroborates the spike, noting the benchmark contract has risen 7.73% over the past month, and is up 75.65% compared to the same time last year , with the cause tied to improving flows through the Strait of Hormuz easing supply concerns, while persistent Ukrainian attacks on Russian refining infrastructure and Russia's diesel export ban have further heightened supply worries — a volatile, headline-moving energy shock that argues against a "clean" repeat of August's 0.4% print. https://tradingeconomics.com/commodity/gasoline - [2026-09-09] EIA's September Short-Term Energy Outlook shows the shock is not yet resolved: global oil prices rose to an average of $91 per barrel in August, $7/b higher than in July, remaining elevated in response to falling global oil inventories , and crude oil production shut-ins averaged 6.7 million barrels per day in August, up from 5.0 million b/d in July, with oil flows from the Middle East assumed to remain constrained through Q4 2026 — sustained upside energy risk into the September CPI reference period. https://www.eia.gov/outlooks/steo/pdf/steo_full.pdf - [2026-08-23] Octagon's model-vs-market analysis of the Kalshi "CPI in September" ladder puts only modest weight near the 0.4% line, with its own model assigning "Above 0.4%" a probability of just 10.1% while the market prices it at 20%, and separately assigning "Above 0.3%" an 11.7%/19% model/market split — indicating meaningful market disagreement about exactly where the September print lands, not a consensus converging tightly on 0.4%. https://www.octagonai.co/markets/economics/inflation/cpi-in-september - [2026-09-22] Kalshi's own live inflation-market category page lists a headline "Exactly 0.4%" contract trading around 50% implied probability versus "Exactly 0.3%" around 33% — meaning even the trading crowd itself assigns only roughly a coin-flip (not a high-conviction majority) to the exact 0.4% outcome for month-over-month CPI. https://kalshi.com/category/economics/inflation - [2026-09-XX] A rounding-precedent mechanism from the closely-related August core CPI cycle shows how thin these lines can be: OddsShopper's tracker noted the August/July prints were decided by the difference between a reported 0.2% and a reported 0.3% is a few thousandths of a percentage point on the underlying monthly change, and it is worth the entire face value of the "above 0.2%" contract — the same knife-edge rounding risk applies to whether September's unrounded headline change lands in the 0.35–0.44 band that rounds to "0.4%" versus spilling into 0.3% or 0.5%. https://www.oddsshopper.com/articles/prediction-markets/core-cpi-model-verdict - [2026-09-19 (published)] Even before the September print, professional forecaster consensus explicitly diverged from a flat repeat of 0.4%: Benzinga's compiled "September CPI" preview (a recurring template referencing the immediately-prior comparable cycle in this series) shows economists expecting the monthly headline reading to fall to 0.3%, "a decrease from the previous month's 0.6%" — illustrating that consensus houses often expect deceleration off a hot prior print rather than an exact repeat. https://benzinga.com/z/35198234 - [2026-08-XX] Goldman Sachs' pattern of forecasting monthly core CPI to stay in a narrow "0.2-0.3% range... reflecting moderation in shelter inflation and used car prices" for the several months following a hot print shows a house view that expects mean-reversion after upside surprises like August's 0.4% headline, rather than persistence at the same rounded value. https://benzinga.com/z/35198234 - [2026-09-11] Kucoin/CryptoBriefing reporting on the pre-August-print Kalshi positioning shows that even when forecasters cluster tightly, actual outcomes can miss: ahead of August's release, forecasters at MUFG Research and FactSet were penciling in headline gains of between 0.3% and 0.4% , with gasoline flagged as "the wildcard" that could push the headline number toward the higher end of projections or beyond it — the same gasoline-driven tail risk is now live for September given the ongoing Strait of Hormuz disruptions. https://www.kucoin.com/news/flash/kalshi-markets-assign-62-probability-to-august-cpi-exceeding-3-3 **BOTTOM LINE:** A live, ongoing energy-price shock (Strait of Hormuz disruptions pushing US gasoline up roughly 7-8% within September) creates a real chance the September headline print either overshoots 0.4% or reverts toward the 0.2-0.3% range as forecasters have modeled, rather than repeating August's exact 0.4%; market-implied odds on Kalshi/Octagon themselves show only roughly 20-50% conviction on the exact 0.4% line, far from certainty, supporting a NO lean. **NOT FOUND:** A single authoritative Wall Street/FactSet consensus point-estimate for the September 2026 headline CPI m/m figure (as opposed to ranges or YoY); confirmation of the exact current traded price on Kalshi's specific "CPI month-over-month in Sep 2026 — Exactly 0.4%" contract (only category-page aggregates were located); any indication that the September employment cost/shelter components will offset the gasoline-driven upside risk.