Before comparing prediction market odds, compare the contract rules

A market title is a summary. The settlement rules determine what must happen for the contract to pay. Two markets can ask whether the same event happens yet use different deadlines, evidence sources or definitions of the event. A price gap between them is not automatically a disagreement about one identical outcome.

Start by saving the precise rule version and observation time for each side. A comparison without the rules can become impossible to reproduce after a page is updated. If you cannot obtain the full rules, record the contracts as not yet comparable.

First, what is the event? An announcement, a signed agreement and an action taking effect are separate milestones. Second, what is the deadline, including the time zone? Third, which source decides the result? A preliminary release and a final official report can disagree.

Fourth, how are cancellations, postponements and revised data treated? Fifth, who resolves a dispute and what payout is possible when the ordinary outcome cannot be established? A contract with a refund or alternative settlement rule has a different payoff from a strict zero-or-one contract.

Suppose Contract A pays Yes if a policy is announced before midnight on 30 June. Contract B pays Yes only if that policy takes effect before the same deadline. An announcement on 29 June with implementation on 1 July satisfies A and fails B. Buying what appears to be the cheap side of each does not lock in a common result.

No quoted prices are needed to detect this mismatch: it is a difference in the underlying event. Only after the outcomes align does it make sense to examine prices, fees, currency, execution and settlement timing. Even matching wording does not guarantee that an apparent cross-venue strategy can be executed.

Write one sentence covering the event, deadline, source and fallback rule for each contract. Mark every difference before calculating a price gap. Keep a separate line for unresolved wording rather than silently assuming the rules match.

See how a prediction market resolves and oracles and disputed resolutions. To compare products before individual contracts, start with our platform comparisons. This article provides an analytical checklist, not a live arbitrage signal.