CPI inflation, year over year

Kalshi vs Polymarket: Will the rate of CPI inflation be above 4.5% for the year ending in December 2026

Last checked 2026-10-19 10:59 UTC. Prices move constantly; the rules comparison is the durable part.

Not verified as the same bet. The venues' published terms differ in ways that could settle differently.

SETTLEMENT_POLICY_MISMATCH — both venues publish settlement policy, but the published texts diverge
SETTLEMENT_GUARANTEE_UNKNOWN — the venue does not publish enough settlement policy to prove what happens in every branch (missing data, cancellation, revision)

In plain words. Where they differ: both venues publish settlement policy, but the published texts diverge; the venue does not publish enough settlement policy to prove what happens in every branch (missing data, cancellation, revision). Kalshi's fine print: the rules omit terms this contract family requires — the measurement basis, the revision rule, or the missing-release branch its peers publish; the rules never say what happens to open positions if the event is canceled, voided, or never takes place; the rules never say whether a later revision of the underlying number changes the outcome; the rules say what settles the contract Yes but never state what settles it No. In an ordinary outcome both contracts pay the same. The difference shows up only in the unusual case those gaps describe — a delayed release, a canceled event, a revised number — which is exactly when a paired position stops being one bet.

The Polymarket leg here is the global venue, which US accounts cannot trade; it is shown for the rules comparison only.

Venue	Contract	YES price	Taker fee at that price
Kalshi	Will the rate of CPI inflation be above 4.5% for the year ending in December 2026? kalshi:KXCPIYOY-26DEC-T4.5 Open on Kalshi	12¢	1.0¢
Polymarket (global)	Will inflation reach more than 4.5% in 2026? polymarket_global:2241741 Open on Polymarket (global)	15¢	set per market

YES price is the best ask at the last check. Fees use each venue's published taker formula at that price — see the fee calculator for any price.

Capital lock-up: about 177.2 days until the later of the two contracts settles.

Kalshi fine-print grade: F (35/100)
−20 FAMILY_POLICY_INCOMPLETE: the rules omit terms this contract family requires — the measurement basis, the revision rule, or the missing-release branch its peers publish
−20 MISSING_CANCELLATION_POLICY: the rules never say what happens to open positions if the event is canceled, voided, or never takes place
−15 MISSING_REVISION_POLICY: the rules never say whether a later revision of the underlying number changes the outcome
−10 MISSING_NEGATIVE_BRANCH: the rules say what settles the contract Yes but never state what settles it No

What Kalshi publishes

If the Consumer Price Index (CPI) increases by more than 4.5% in the twelve months ending December 2026 (as represented by the one-decimal place value reported by the Bureau of Labor Statistics), then the market resolves to Yes. 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