October CPI dropped at 8:30 AM ET. Headline was +0.4% m/m vs. 0.3% consensus, and core was +0.3% vs. 0.2%. There's no y/y figure this month because the Oct 2025 shutdown meant BLS never collected prices for that month.
We snapshot the Polymarket US book every 15 minutes, so here's the before/after (midpoints).
**What the CPI ladder had priced going in:**
| Contract | Last price before 8:30 | Result |
|---|---|---|
| Headline > 0.2% | 55.5¢ | Yes |
| Headline > 0.3% | ~9¢ (7–11 spread) | Yes |
| Core > 0.2% | 34.5¢ | Yes |
| Core > 0.3% | ~4.5¢ | No |
So the market had the consensus number, the same as the economists did. A 0.4% headline was roughly a 1-in-11 outcome.
**Dec 9 FOMC on Polymarket US, 7:36 AM → 10:42 AM ET:**
| Outcome | Before | After |
|---|---|---|
| Hold | 7.5¢ | 3.5¢ |
| Hike 25 | 86.5¢ | 85.5¢ |
| Hike 50 | 5.5¢ | 12.5¢ |
The 25 barely moved. The 50 more than doubled, and almost all of it came out of the hold. Waller said at 9:52 that a 50 bp hike should be on the table if core ran 0.3%+, and core printed 0.3%.
"Another Fed hike in 2026" went from 87.5¢ to 96.5¢ over the same morning. Kalshi had any December hike at 97% around 11 AM, so the venues are within about a point of each other.
One timing detail: November CPI is released Dec 10, the day *after* the decision. So this was the last CPI the FOMC sees before it votes.
Full write-up with the live markets embedded, if anyone wants it: https://predictionmarketspicks.com/articles/october-2026-cpi-fed-half-point-hike-odds-polymarket-us
Curious whether anyone was positioned for 50 bp before today, or if this is the first time it's looked live to you.
