Why Contract Settlement Rules Matter

Two contracts describing the same event are only equivalent if their resolution criteria, sources, timing and cancellation policies line up.

The checklist

• Contract wording — literally compare the title and description. "Candidate X wins" vs "Candidate X wins the popular vote" are different events.
• Resolution criteria — what condition triggers the payout?
• Resolution source — who decides? An exchange rulebook, an oracle, a news outlet, a government agency?
• Settlement date — the same event can settle on different dates on different platforms.
• Event definition — start and end boundaries ("in 2026" vs "by Dec 31").
• Cancellation policies — what happens if the event is postponed, canceled, or becomes ambiguous? Some platforms refund; some resolve on their own rules.
• Platform-specific rules — fee treatment at resolution, dispute processes, market-recognition policies.

A concrete warning

"Kalshi specifies certification by Congress while Polymarket specifies declaration by the Associated Press." In most elections these agree. In a contested one, they can disagree for weeks — exactly when the arbitrage looks most attractive and is most dangerous.