September 2026 CPI Release

The September CPI report is due October 14 at 8:30am ET, and the book has moved up again this week. August printed 3.4% headline year over year and 2.4% core.

Headline: the month-over-month chain is the busiest book on the page, $178,881 today, and it centers on a hot month: Above 0.4% is 86.5%, Above 0.5% 53.5%, the busiest rung at $120,138, and Above 0.6% 20.5%. Year over year, Above 3.5% is 82.5% and Above 3.6% 38%, so the modal print is 3.6%, two ticks above August; the exact-value board agrees at 44%.

Core: Above 2.4% is 47.5%, down from 61.5% a week ago, and took $22,820 of the core chain's $24,255 day. With Above 2.3% at 82.5% and Above 2.5% at 12.5%, a 2.4% and a 2.5% core print are priced about evenly, near 35% each.

This workspace tracked five consecutive upside misses across the July and August releases. The September book now prices a hotter headline month in advance; whether it has priced enough is what October 14 settles.

Kalshi's cumulative September chains, displayed in their native form. Cumulative markets price "above X", so each step down the ladder is the probability the print clears that threshold; the gap between two adjacent strikes is the odds of landing exactly in between.

With six days to go the books are trading: $178,881 on the month-over-month chain, $16,344 on headline year over year and $24,255 on core. Headline YoY is near-certain through Above 3.4% (96.5%), 82.5% at Above 3.5% and 38% at Above 3.6%. Core YoY runs 82.5% above 2.3%, 47.5% above 2.4% and 12.5% above 2.5%.

The Categorical books sit beside the chains. They express the same question as a discrete distribution rather than a ladder.

The headline YoY Categorical centers on 3.6% at 44%, with 3.7% at 26.5%, 3.5% at 12% and 3.8% at 7%, on $1,008. The month-over-month Categorical is still not readable: its strikes carry stale marks, 0.1% at 96% and 0.2% at 92%, that cannot all be true at once, and its $746 today all went to Exactly 0.7% at 16%. Use the chain for month-over-month.

Core month-over-month prices Above 0.1% at 80.5%, Above 0.2% at 36.5% and Above 0.3% at 9.5%, on $15,104: the weight is on a 0.2% core month.

The annual context widgets round out the stack: Polymarket's 2026 inflation-ceiling book, where Above 4.5% is 12.5% and Above 5% 7.5%, and the Manifold binary on whether 2026 inflation runs higher than 2025's, at 60%.

• A hot headline month is the base case. Above 0.5% month over month at 53.5% took $120,138, the most of any strike on the page. Year over year the mode is 3.6%, two ticks above August.
• Core has cooled in the book. Above 2.4% went from 61.5% to 47.5% this week, leaving 2.4% and 2.5% priced about evenly.
• The year's ceiling. Polymarket prices inflation above 4.5% at some point in 2026 at 12.5%, down from 16.5%.
• Thin Categoricals. The month-over-month exact board's marks are not prices. Trust the cumulative ladders.
• Next release: October 14, 8:30am ET, covering September data. The countdown at the top of the page tracks it.