Polymarket vs Kalshi: two event venues, check which one you opened

A designated contract market is a US derivatives exchange under the Commodity Exchange Act. The CFTC's industry-filings list is the document, not a blog.

Kalshi's row says the organisation was designated on 3 November 2020. The remark on that row, and the amended order itself, say that on 17 January 2025 the Commission granted Kalshi's petition to modify the order so futures commission merchants may intermediate trades. The amended order also says Kalshi must keep complying with the Act and with DCM core principles, and that the Commission can modify or restrict the designation.

Polymarket US is a different row: QCX LLC, doing business as Polymarket US, designated on 9 July 2025. The remark says QCX LLC operates under that assumed name. If you are not on that venue, you are not on that designation.

This note lives in Foundations because people search the brand pair. It is not a recommendation to trade either market. Is Kalshi gambling takes the classification question. How Polymarket works is the mechanics page for that brand.

The Congressional Research Service, in "Prediction Markets: Policy Issues for Congress" (IF13187), describes the split in plain language. Kalshi runs a CFTC-regulated exchange. Polymarket's largest prediction-market exchange is described as domiciled offshore and as claiming to block US users, so that offshore exchange is not effectively under CFTC rules. The same note says Polymarket has acquired a smaller CFTC-approved exchange for US customers, which is a dual structure.

That is why "Polymarket" in a headline is not yet a fact. Look at the legal name on the account you opened and match it to the CFTC row. A geo-block, a terms-of-service line, and a designation order are three different sentences.

Contracts on these venues are typically quoted in cents or as a price between zero and one, which people translate into a probability. The translation is a price. It is not a promise that the event will happen that often, and it ignores fees. Expected value is the arithmetic once you know the fee. This page does not know today's fee.

A house roulette wheel publishes pockets and a payout. Your result does not depend on another customer's opinion. An event contract is a trade against someone who wants the other side, cleared under the venue's rules, and settled when the venue says the event resolved.

Losing a contract can still wipe the stake. Resolution can be disputed. You may be unable to exit if the book is thin. None of that is fixed by calling the price a probability.

PVPspinArena does not list event contracts. The games it does run are described on how it works. Do not use a coinflip as a substitute for a contract you meant to buy, or the reverse.

Adults only. If the position is money you cannot afford to lose, stop. Responsible gambling applies even when the product is filed as a derivative.

Write the legal entity, the URL, and the date. Then open the CFTC designated-contract-market list and see whether that entity is on it. If the row has moved, the row wins and this paragraph is stale.

Do not copy a fee, a geo-block, or a list of allowed contracts from a screenshot. House edge will not describe these venues, because they are not priced as a fixed house percentage. If someone sells "Polymarket versus Kalshi" as a profit method, they are selling a story about two order books.