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No. Do not treat Polymarket Gamma API’s endDate as a universal resolution deadline. Polymarket says each market’s written rules define how it resolves, and a limited sample found that endDate corresponded to different moments across market types. To understand a specific market, read its rules and check its current state.
What does Gamma API’s endDate tell you?
It gives you a timestamp associated with a market record, but the field alone does not establish whether trading stops then or when the outcome will be finalized. Polymarket’s Gamma API documentation shows market- and event-level records, including fields such as endDate, description, active, closed, and acceptingOrders. The documented example is one record, not a definition that makes endDate mean the same thing for every market. Polymarket Institute’s Gamma API overview describes the available data and example record.
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For resolution, Polymarket’s rule is explicit: “The market title describes the market, but the rules define how it should be resolved.” The market’s rules identify the resolution source, its end date, and relevant edge cases. Read the actual rules rather than infer a deadline from a title or timestamp. Polymarket Help Center: How Are Markets Clarified?
Does trading stop at endDate?
Not necessarily. A scheduled timestamp is not, by itself, proof that the market has stopped accepting orders. For the current trading state, inspect the market’s latest Gamma record, including closed and acceptingOrders, and fetch the data again when making a time-sensitive decision. These fields appear in Polymarket’s documented record example; the practical interpretation is to use them as current-state indicators, not as substitutes for the market rules.
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Keep three moments distinct: the event or deadline described in the rules, the point at which the market closes to trading, and final resolution. They can be related, but the endDate field alone does not prove they coincide.
What do observed endDate patterns show?
A September 24, 2026 analysis by OrcaLayer Research compared 23 hand-picked international markets fetched from Gamma API. In that sample, reported patterns varied by market type:
| Sample type | Observed pattern | Sample and limits |
|---|---|---|
| Esports | endDate was exactly six hours after scheduled start. |
4 of 4 sampled markets; OrcaLayer Research, September 24, 2026. |
| Tennis | endDate was exactly seven days after the original scheduled start. |
4 of 4 sampled markets; OrcaLayer Research, September 24, 2026. |
| NFL, college football, and soccer | endDate equaled kickoff. |
4 of 4 sampled matches; OrcaLayer Research, September 24, 2026. |
These are observations from a small, hand-picked sample, not platform-wide rates or guarantees. The analysis does not establish that every market of a given type follows the same pattern, and it concerns the international Gamma API, not Polymarket US. OrcaLayer Research’s September 2026 analysis describes its sample and limitations.
When is a market actually resolved?
Market closure and final resolution are separate. Polymarket describes a process in which an outcome is proposed, followed by a two-hour challenge period before final resolution. Its help article says winning shares receive $1 per share after resolution; that is the process and payout description in Polymarket’s current guidance, not independent legal or financial advice. Polymarket Help Center: How Are Prediction Markets Resolved?
How to check a specific market
- Open the market’s rules. Find the written description and identify the outcome criteria, named resolution source, applicable end date, and any postponement or exception language.
- Compare the record with the rules. Review
descriptionand any relevant title or group label alongsideendDate. Treat the rules as authoritative if a timestamp seems inconsistent with their stated deadline. - Check current trading state. Fetch the Gamma record again and inspect
closedandacceptingOrdersrather than assuming that a scheduledendDatemeans trading has ended. - Wait for resolution status. Do not equate a passed timestamp or a closed market with a final outcome; the documented proposal and challenge process still matters.
Which source should you trust?
For the outcome and deadline, prioritize the market-specific written rule and its named resolution source. Use Gamma fields to understand the record and check current state, and treat empirical timing patterns as clues—not universal rules. A timestamp is useful context; it is not a replacement for the market’s terms.
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