Parimutuel pool

This is the third mechanism, after a book and a curve, and it is the one a reader is most likely to meet without being told which one they are looking at. It produces a percentage that sits on a screen looking exactly like a price, and it is not a price.

How it works

There is no trade. Everyone entering an outcome pays into that outcome's pool. The pools close, the event happens, the operator takes a cut, and the winning pool divides what is left in proportion to what each holder put in. Zeitgeist's documentation states the general form — the return for each unit staked on an outcome is the sum of all stakes divided by the stake on that outcome. PancakeSwap's Prediction product, a five-minute crypto price game rather than a venue in this catalogue, publishes the same arithmetic as a ratio you can read off the screen mid-round: the payout ratio for a pool is the total value of both pools divided by the value of that pool, with 3% of each round's prize pool going to the treasury.

Read the formula once more, because the whole difference is inside it. The denominator is still moving. A price you take on a book or a curve is fixed at the moment you take it. An implied price in a pool is provisional until the pool closes, and if your side fills up behind you, your return shrinks without anything about your own entry having changed. There is nothing to arbitrage and no price to check, because there is nothing tradeable until settlement.

You cannot get out

Zeitgeist's documentation says it in as many words — there is no selling of contracts, and once you hold one you hold it. Trepa's founders, closing a pari-mutuel accuracy contest in August 2026, listed the same two properties as the known price of the mechanism: "No fixed odds, so you cannot know your payout when you commit, and no way out of a position once entered."

It needs a crowd in the same window, not just a crowd

The other structural property, and the one that killed the clearest recent implementation. Trepa ran a single live hour a day, 1 to 2pm UTC, and wrote afterwards that "a pari-mutuel pool with proportional scoring needs a crowd predicting in the same window. Thin pools mean small payouts, unstable variance and a worse experience for everyone in them." The scaling plan — more assets, more windows — diluted the one thing the mechanism required. A book or a curve tolerates a trader arriving alone at three in the morning. A pool does not.

What the catalogue records

parimutuel is one of the five values economics.liquidity_model can take, and no card here sets it. That is not an oversight, it is the finding: 46 cards carry clob, 6 carry amm, 8 carry none, and none carry this. The shape exists in the sector and not in the listing. Zeitgeist implemented one in its runtime, next to an AMM and an order book, and its chain stopped producing blocks in August 2026. Trepa built a whole product on one and closed the same month. PancakeSwap's rounds are a crypto price game, not a prediction market venue, and are cited here only because the documentation states the arithmetic outright.

So the "Where you will meet this" block on this page is empty, and that is the correct answer. The term earns a page because the corpus keeps having to explain what a venue is not doing.

Why it matters here

You will read the ratio as a probability. On a book, a tight two-sided price near 50 is the market saying something. In a pool, a 50/50 split of the money says only that the money is split; it has no bid and no ask behind it and nobody was required to stand behind the number.

You will plan an exit you do not have. Every risk calculation that assumes you can cut a position is wrong here. Sizing follows from that — the only sensible stake in a pool is one you are content to carry to resolution, because that is the only way it ends.

You will apply the wrong fee model. There is no taker fee, so the effective fee at fifty cents does not describe anything. The cut comes out of the pool once, at settlement, which also means the losing side pays it. What a trade actually costs covers the four bases venues do publish and why none of them fits this one.

You will assume a crowd will arrive. On a curve, liquidity is already funded and waiting. In a pool, the depth is whoever happens to be in the same window as you, and an empty pool is not thin — it is nothing.