# Settlement source

Also written resolution source, source agency.

*https://predictionmarkets.tools/glossary/settlement-source · next to Prediction Market Venues*

**Definition:** The named publication, data feed or organisation whose figure decides a contract, as written in its rules before trading opens: a government report, a league's official result, a named news outlet, a price feed. It is not whoever reads that figure and declares the outcome, and it is not the question in the market's title. Two venues listing the same question can name different sources and settle differently.

A market asks whether it will be hotter than 85 degrees in New York tomorrow. The reader answers
the question in the title. The contract answers a narrower one: what one named document will say
about one named place, at one named time. Those usually agree, and the page exists for the days
they do not.

## How it works

**The source is named in the rules, not chosen afterwards.** Every exchange and oracle venue in this
catalogue writes down, before trading opens, where the deciding figure comes from. The
names differ. Kalshi and ForecastEx terms speak of a *source agency*; the Polymarket US rulebook
uses the same phrase for the exchange itself and lists the external sources under it as primary,
secondary and tertiary; Polymarket's international markets, Myriad and Futuur put the source
inside the rules prose; Limitless names a price oracle by market type. This
site calls all of them the settlement source, and the card field `markets.resolution_source`
records it together with who applies it.

**On a US exchange the choice is regulated.** Core Principle 3 of the Commodity Exchange Act, at
7 U.S.C. 7(d)(3), says the board of trade — the designated contract market — "shall list on the contract market only
contracts that are not readily susceptible to manipulation". The Commission's guidance on how to
show that, Appendix C to 17 CFR Part 38, says a cash settlement price "should be reliable,
acceptable, publicly available, and reported in a timely manner", and that where an independent private third
party calculates it, the exchange should consider the need for a licensing agreement and should,
where practicable, enter an information-sharing agreement with that provider. That is guidance about what to demonstrate, not a list of approved
sources, and the exchange still picks.

**Off-chain rules, on-chain readers.** On an oracle venue the source is text the oracle is asked to
apply. UMA's own description is that each request includes "detailed instructions on how the
request should be resolved", which proposers read before proposing an answer. If the named source
is ambiguous, the dispute is about the text, and it is settled by a vote — covered under
[optimistic oracle](https://predictionmarkets.tools/glossary/optimistic-oracle).

### The source is not the authority

Two separate questions hide under "who resolves this market". **What does it resolve against** —
the settlement source. **Who reads that source and declares the outcome** — the exchange's markets
team, a token-holder vote, a question's author. The Kalshi card records both in one line: Kalshi's
markets team, as the exchange, against the source named in each market's rules. The Polymarket
card records the same kind of named source with a different authority: a bonded proposal to UMA's
optimistic oracle. The authority side, with its timetables
and appeals, is in [who decides the outcome](https://predictionmarkets.tools/guides/who-decides-the-outcome).

### Which version of the figure counts

A source publishes more than once. The ForecastEx card records a building-permits contract naming
the US Census Bureau and stating that only the initial release counts; later revisions do not
change the outcome. A US weather station's daily climate report is itself preliminary, which the
[temperature guide](https://predictionmarkets.tools/guides/what-a-temperature-market-settles-on) sets out at length. The
settlement source is therefore a document *and a moment*: the first print, the report at 8:00 AM
the next day, the figure as of a stated cutoff.

## Why it matters here

**The same question on two venues is two contracts.** The Polymarket US card records its New York
temperature markets settling on the National Weather Service Daily Climate Report for the Central
Park station. The Kalshi API card, verified on 19 September 2026, records the settlement source for
its NYC temperature series as The Weather Company, which Kalshi took on as its weather source in August 2026. Two identical
titles, two documents; on the day those documents disagree by a degree, one venue pays Yes and the
other pays No. Anyone pairing markets across venues — for a spread, a hedge or a dashboard — has
to pair them on the source, not on the title. The
[cross-venue matching how-to](https://predictionmarkets.tools/how-to/match-a-question-across-venues) is built around that.

**A source can change under a live series.** The Kalshi weather switch above is one case: an
archived copy of the same NYC series record from 14 February 2026 lists the NWS Climatological
Report as its settlement source, with a note that the NWS Daily Climate Report is the official
and final value. The
[who decides the outcome](https://predictionmarkets.tools/guides/who-decides-the-outcome) guide records rules that let an exchange
designate a replacement source after trading has started. A source read once, at listing, is the
source as of listing.

**It is the part of a market a machine can read, on one venue.** The Kalshi API card records a
`settlement_sources` list of names and URLs on every series record, readable without an account.
Elsewhere in this catalogue the source is a sentence inside rules prose and has to be parsed out.
The mechanics of fetching it are in
[how to read a market's rules from the API](https://predictionmarkets.tools/how-to/read-a-markets-rules-from-the-api); this page
only says why it is worth the fetch.

**The card field is not the source list.** `markets.resolution_source` on a venue card is one line
saying who resolves and against what kind of source. It cannot carry the source for every market,
and on a data tool, a client library or a dashboard it is `null`, because those products settle
nothing: the settlement source belongs to the venue whose data they carry.

**Being right about the world is not the same as being right about the source.** A reader who
correctly calls the revised inflation figure, the airport that was hotter than the park, or the
league result after an appeal can still hold the losing side, because the contract named a
different document or an earlier moment. That gap is where positions that looked correct settle against
their holders, and it is visible in the rules before the trade, not only after it.

## Where you will meet this

- [ForecastEx](https://predictionmarkets.tools/tools/forecastex.md)
- [Futuur](https://predictionmarkets.tools/tools/futuur.md)
- [Kalshi API](https://predictionmarkets.tools/tools/kalshi-api.md)
- [kalshi-python](https://predictionmarkets.tools/tools/kalshi-python.md)
- [Kalshi](https://predictionmarkets.tools/tools/kalshi.md)
- [Myriad](https://predictionmarkets.tools/tools/myriad.md)
- [Polymarket US](https://predictionmarkets.tools/tools/polymarket-us.md)

## Sources

1. [17 CFR Part 38, Appendix C — Demonstration of Compliance That a Contract Is Not Readily Susceptible to Manipulation (revised as of April 1, 2025)](https://www.govinfo.gov/content/pkg/CFR-2025-title17-vol1/xml/CFR-2025-title17-vol1-part38-appC.xml) — Office of the Federal Register and Government Publishing Office, 2025-04-01
2. [7 U.S.C. 7, Designation of boards of trade as contract markets (2024 edition of the United States Code)](https://www.govinfo.gov/content/pkg/USCODE-2024-title7/html/USCODE-2024-title7-chap1-sec7.htm) — Office of the Law Revision Counsel, U.S. House of Representatives, read 2026-09-27
3. [Kalshi series record KXHIGHNY, "Highest temperature in NYC", as it stood before the August 2026 switch (Internet Archive capture)](https://web.archive.org/web/20260214013603/https://api.elections.kalshi.com/trade-api/v2/series/KXHIGHNY) — KalshiEX LLC, archived by the Internet Archive, 2026-02-14
4. [How does UMA's oracle work?](https://docs.uma.xyz/protocol-overview/how-does-umas-oracle-work) — UMA Protocol, read 2026-09-27

*Last updated 2026-09-27. A reference page, corrected in place — not a dated post.*