Grade B · 95%Near equivalentOutcome mapping: same

Kalshi vs Polymarket: Will Michelle Obama be the Democratic Presidential nominee in 2028

Two contracts on the same event, priced by two separate crowds. Where they disagree, one of them is wrong — or the contracts are not quite the same question.

Live comparison

Kalshi

1.6%

−0.1 pts

Polymarket

0.5%

—

Disagreement: 1.0 pts
Match confidence: 95%
Theoretical edge: none

Side by side

Metric	Kalshi	Polymarket
Probability	1.6%	0.5%
1h move	0.0 pts unchanged	0.0 pts unchanged
24h move	−0.1 pts down	—
7d move	—	+0.1 pts up
24h volume	$4,019	$13,477
Liquidity	$1,841	$1.84M
Spread	0.1¢	0.1¢
Open interest	5,398,661	—
Closes	Nov 7, 10:00 ET	Nov 7, 23:59 ET
Resolution source	https://democrats.org/	—
Contract	Open →	Open →

Probability history

Both venues on one axis, with the gap beneath

KalshiPolymarket

Gap history (percentage points)

How confident is this match?

Deterministic scoring first; the model may only downgrade

Title: 79%
Entities: 50%
Dates: 100%
Threshold: 100%
Polarity: 100%
Rules: 65%

Deterministic score 79%. Semantic verification 95%. Last verified Sep 22, 07:04 ET.

Material differences

The Kalshi contract explicitly requires the nominee to 'accept' the nomination in its rules text ('wins and accepts'), while the Polymarket rule also includes 'accepts'. Both are aligned on this condition.
The Kalshi resolution source is specifically https://democrats.org/, whereas Polymarket uses a 'consensus of official Democratic Party sources'. These are functionally equivalent for determining the official nominee.
Polymarket explicitly states that replacement of the nominee before election day does not change the resolution. Kalshi's rule implies the same by focusing on who wins and accepts the nomination at the convention, but lacks the explicit anti-replacement clause. However, since both resolve based on the convention outcome (winning/accepting), they settle on the same real-world event: Michelle Obama'
Close times differ slightly (Nov 7 vs Nov 8 UTC), but settlement occurs after the convention concludes, so this timing difference is immaterial to the final outcome.
The Kalshi contract has a specific resolution source URL (https://democrats.org/), while the Polymarket contract relies on a 'consensus of official Democratic Party sources'.
The Polymarket rules explicitly state that any replacement of the nominee before election day will not change the resolution, whereas the Kalshi rules do not contain this explicit exclusion clause, though it is implied by the standard definition of winning and accepting the nomination at the convention.
The Kalshi contract explicitly requires the nominee to 'accept' the nomination in its rules text ('wins and accepts'), while the Polymarket rules also require acceptance ('wins and accepts'). This is consistent.
Polymarket includes a specific clause: 'Any replacement of the democratic nominee before election day will not change the resolution of the market.' Kalshi's provided rules do not explicitly state this, but standard Democratic Party convention (and the implied 'nominee' status) generally means the person who receives the majority of delegate votes at the convention is the nominee, regardless of if
The close/settlement times differ slightly: Kalshi settles on 2028-11-07 15:00 UTC, while Polymarket closes on 2028-11-08 04:59 UTC. However, since the event (Democratic National Convention) typically occurs in August/July 2028, well before November, both contracts will have settled long before these cutoffs based on the actual outcome. The difference in cutoff dates does not affect the settlement
The Kalshi contract explicitly requires the nominee to 'accept' the nomination for a YES resolution. The Polymarket contract also requires the individual to 'win and accept' the nomination.
Polymarket includes an explicit clause stating that any replacement of the Democratic nominee before election day will not change the resolution (i.e., if she wins/accepts but is later replaced, it still resolves YES). Kalshi's rules do not explicitly mention this edge case, but standard interpretation of 'wins and accepts' usually implies the act of acceptance at the convention locks in the YES,;
Different close/settlement times: Kalshi closes 2028-11-07 15:00 UTC, Polymarket closes 2028-11-08 04:59 UTC. This is a minor timing difference unlikely to affect settlement outcome given the event occurs months prior.

Both contracts ask if Michelle Obama will win and accept the 2028 Democratic presidential nomination. The conditions for YES are identical: she must be the nominee chosen by the party. The slight differences in resolution source wording and close time do not affect the settlement logic regarding the specific individual named.

Theoretical cross-market edge

Grade A pairs only, from executable book prices with depth simulation

Theoretical edge is calculated only for Grade A pairs, where the two contracts appear materially equivalent for settlement analysis. This pair is graded B, so the venues are compared for probability and sentiment only.

Why are these diverging?

Explanation pending

An evidence-grounded explanation is written once this market gathers enough confirmed price and trade evidence. Every number on this page is already live.

Event timeline

No timeline events yet

Timeline entries appear once price or trade activity crosses a reporting threshold.

Notable trades on both venues

Past 24 hours, ranked by notional

No sizeable trades recorded

Neither venue has printed a trade above the reporting threshold on this event in the last 24 hours.