Why the same contract costs two different prices on two venues

A reader arrives at this question holding two screens. The same outcome is quoted at 62 cents on one venue and 57 on another, the event is the same event, and the difference looks like an oversight.

It is not an oversight, and it is not one number. It is the sum of a list of differences, each of which has a document behind it: two rule texts that can resolve opposite ways on the same afternoon, two fee schedules charged on quantities that are not the same quantity, collateral denominated in two different things, two exits with different costs and different delays, and eligibility rules that frequently mean one person cannot hold both sides at all.

This page takes that list apart so the two quotes can be compared. It does not tell you what to do with the difference, and it does not describe a procedure for capturing one.

How it works

The two quotes are quotes on two different contracts

The cleanest way to see how much definition sits under a short question is to read a filed one. KalshiEX LLC self-certified a head-to-head motorsport contract with the CFTC under Regulation 40.2(a) on 23 March 2026 — a routine filing, for the sort of market whose title is one line. Its Appendix A runs to a dozen pages, and the parts that decide who is paid are these:

• A hierarchy of sources, not a source. The terms name the Source Agencies "in hierarchical order": the governing body, the official website or app of the series, then ESPN, Sky Sports, Motorsport.com, Autosport, the Associated Press, BBC Sport and Reuters. Two venues writing the same question will rarely name the same list, and never in the same order.
• A tie is not a win. "A tie on <metric> does not constitute <competitor 1> beating <competitor 2>" — the contract resolves No. That is an answer to a question most titles do not ask.
• Late corrections do not count. Revisions to the underlying made after expiration are not accounted for, and decisions issued after the official final classification is published are not incorporated.
• A cancelled or moved event has a price. If the session is cancelled outright, or postponed to a start more than 48 hours later, or the event moves to a different venue, contracts resolve at the last fair market price.
• The clock is written down. The Last Trading Date and Time are the same as expiration, the expiration time is 10:00 AM ET, the latest expiration date is one week after the scheduled session, and the Settlement Date is no later than the day after expiration unless the outcome is under review.

None of that is unusual. It is what a contract listed on a designated contract market looks like — the CFTC's own description of a DCM is an exchange operating under its oversight pursuant to Section 5 of the Commodity Exchange Act, subject to core principles that include contracts not being readily subject to manipulation.

Now put a second venue's version of "the same" question beside it. Polymarket US documents its rules as four parts: resolution criteria, qualifying requirements that carry the edge cases, a resolution timeframe, and resolution sources — of which it says plainly that unlisted sources "have no effect". Some markets there carry alternative settlement terms, a 50-50 split among them. The exchange determines the result "using publicly verifiable information", after the outcome is publicly confirmed.

Limitless resolves most markets from a price feed: Pyth Network handles the majority automatically at the deadline, a Chainlink time-weighted average price resolves short-cadence crypto markets, and custom event markets are reviewed by the team, which its documentation puts at 24 to 72 hours after the deadline.

Three venues, three different answers to "who reads what, and when". The gap between two quoted prices is partly the market's opinion of those differences.

The fallback prices are different, and a two-leg position gets one of each

The place this bites hardest is the case nobody prices: the question that cannot be answered cleanly.

The filed Kalshi terms settle a cancelled session at the last fair market price — whatever the market thought just before the news. Polymarket US's rule structure provides for alternative settlement terms written into the market, such as a 50-50 split. Limitless's refund policy covers a market resolved to the wrong outcome, and what it returns is not a dollar: if you held shares on the side that should have won you receive "a refund equal to the amount you originally paid for those shares", and if you held the side that wrongly won you keep the payout, because on-chain settlements cannot be reversed.

Two positions taken to hedge each other therefore have two different disaster cases, and they do not cancel out. Who decides, from which document, and what the fallback is on each venue is a page of its own: who decides how a prediction market resolves sets out the four kinds of decider and where each one's fallback is written.

The clocks are not the same clock

On the filed Kalshi contract, the last trade and expiration are the same moment, expiration is 10:00 AM ET, and settlement follows no later than the next day unless the outcome is under review.

Polymarket US operates "nearly 24/7, with a recurring weekly maintenance window every Thursday from 2:00-4:00 AM ET", reports daily as of 5:00 PM ET, and settles winning contracts at $1.00 and losing ones at $0.00 through Polymarket Clearing once the outcome is finalised. Its resolution page is explicit that the timeline varies by market type — sports quickly, political and news markets pending certification or official publication.

On the on-chain side the delay has a mechanism with a published shape. An outcome is proposed against a bond; a disputer posts a bond of their own; and where the dispute escalates, UMA's own documentation describes a 24-hour commit period followed by a 24-hour reveal period, with the dispute resolving when a minimum 65% majority of staked UMA lands on a single outcome.

A position held across two venues is released twice, on two timetables, and the later one is the one that governs the capital.

The collateral is two different objects

Both venues will tell you a contract pays a dollar. They do not mean the same dollar.

Polymarket US documents fully-collateralised contracts, in which "sufficient funds are locked to cover the maximum possible payout at the time the trade is executed". A buyer posts the price and no more; a seller receives the sale proceeds and posts $1.00 of margin per contract, held by Polymarket Clearing against the payout. There is no leverage, and maximum gain and loss are fixed at execution.

ForecastEx states the same principle in one sentence from the other end: "Contracts are fully secured by cash deposited by the Member prior to their bids being accepted", settling at $1.00 or $0 at expiration. It is also the one venue in this catalogue that pays you for the wait — it invests that cash and, by its own FAQ, "passes 100% the earnings back to the Members each month" as an Incentive Coupon.

Limitless holds nothing: "Limitless does not hold a platform balance" and "Your USDC always lives in your wallet on Base". Gas is yours to pay in ETH on an external or embedded wallet, and sponsored by the platform on a smart wallet.

That difference reaches the price through the unit itself. Circle describes USDC as 100% backed by highly liquid cash and cash-equivalent assets and redeemable 1:1 for US dollars, and in the same breath describes who may do that redeeming: Circle Mint serves exchanges, institutional traders, banks and large financial institutions, and "Mint is not available to individuals or small businesses". A retail holder's route back to dollars is an exchange or an on/off-ramp provider, at that provider's price, and the token is native on 38 chains as of 16 September 2026 — of which Limitless credits deposits and withdrawals on exactly one, Base. A dollar on a CFTC-regulated exchange and a dollar of USDC in your own wallet are not interchangeable at par without somebody's fee and somebody's delay in between.

One person frequently cannot hold both legs

This is the constraint that removes the question entirely, and it is written in the terms rather than in the product.

Limitless's terms of service, effective 15 September 2026, say the platform is not available for trading to users from the United States of America, the Republic of China, and the Canadian provinces of Ontario and Alberta, and is not available at all to users accessing it from Russia, Belarus, Cuba, Iran, North Korea, Syria and the Crimea, Donetsk and Luhansk regions. Users must be at least 18 or the age of legal majority where they are, whichever is higher, and must not appear on the OFAC list of Specially Designated Nationals.

Polymarket US requires identity verification "to comply with federal identity and anti-money-laundering (AML) rules" before you can deposit or trade: full name, date of birth, residential address and a username, with a government-issued ID and a selfie where enhanced verification is triggered. Most verifications complete instantly; a manual review takes 3 to 5 business days.

And a filed contract can bar you by occupation rather than by country. Appendix B of the Kalshi filing prohibits under-18s from holding accounts and then bars, for that contract, officials and timing and scoring personnel of the governing body, competitors and team staff, employees of the series' commercial rights holder, employees of official tyre, fuel and parts suppliers — and the immediate family and household members of all of them.

Two guides carry those two mechanisms in full: why a venue is unavailable where you are and what you have to prove to trade.

What it costs

Every row below is a real charge or a real delay standing between two quoted numbers. Only the first two appear as a rate anywhere.

The two fees are not in the same unit

Polymarket US charges a symmetric coefficient: "Fee = Θ × C × p × (1 - p)", with a taker theta of 0.0695 — a maximum of $1.74 per 100 contracts at 50 cents — and a maker rebate at a theta of -0.0125, a maximum of -$0.31 on the same trade. Fees and rebates are rounded to the nearest cent using banker's rounding, and the schedule reads "Effective exchange-wide from 12 AM ET, Thursday September 17, 2026."

Limitless charges takers only: buys on the order book carry "0.40% - 3.00%" paid in outcome tokens, sells "0.42% - 1.50%" paid in USDC collateral, and AMM markets a flat 0.40%. Makers pay nothing.

Those two numbers cannot be subtracted from one another as published, because one is a coefficient on price times one minus price and the other is a percentage of what the fill costs. Converting them to a common measure — cost per dollar of payout — is the whole subject of what a trade actually costs, and it is the first thing to do to a two-venue comparison. Doing it in the wrong unit reverses the ranking, which that page demonstrates with a published 3.00% that is cheaper than a published 1.75%.

The capital is committed twice, and released twice

Buy the Yes side at 62 cents on one venue and the No side at 35 on another and you have committed 97 cents to a pair that pays a dollar — in two places, in two currencies, under two sets of rules. Neither venue nets the other: Polymarket US locks funds covering the maximum payout at execution, ForecastEx requires the cash before the bid is accepted, and nothing in either document contemplates a position held somewhere else. If either leg is sold short rather than bought, the margin is the full $1.00 per contract.

Put a number on the wait, because it is usually larger than the fee on a long-dated market. At an assumed 4% a year, $1,000 committed for 30 days is about $3.29 and for six months about $20, against trading fees that run in the region of 1 to 2% of a contract's payout. The commitment ends at resolution on each venue separately, and the filed Kalshi terms allow expiration as late as one week after the scheduled session, with settlement the day after that unless the outcome is under review.

Getting out is priced differently on each side

Polymarket US processes withdrawals back to the funding method — "All withdrawals must return to the same payment method used for deposit. Funds cannot be redirected to new or third-party accounts" — in the order the deposits were made, with debit card and ACH clearing in 3 to 4 business days and wire in 1. Money that has landed but not cleared can be traded and cannot be withdrawn.

Limitless has nothing to release, because the USDC never left your wallet; what it costs instead is a chain transaction, gas in ETH unless you are on a smart wallet, and the discipline of sending on Base and nowhere else. The full shape of both exits, including promotional credit that never leaves at all, is in how money gets back out.

What you can do about it

Convert both quotes to one measure before comparing them. Price plus the fee converted to cost per dollar of payout, on each venue, plus what the exit will take. Compare the pair against the $1.00 the contract pays, not against each other. Two raw quotes are two numbers in different units, and the gap between them is not yet a quantity.

Read the two rule texts, not the two titles. Find the named sources and their order, what a tie does, what happens if the event is cancelled or moved, what the last trading time is, and what the fallback price is. On a US exchange the operative text is the filed contract terms — the CFTC's product filings carry them, which is where the motorsport terms quoted above were read. If the two texts name different sources or different fallbacks, the two prices are answering different questions and the difference between them is not an error to be corrected.

Line the clocks up. Last trading time on each venue, the resolution timetable on each, and the settlement date on each. Two legs that close at different times are unhedged in between, and an oracle dispute on the on-chain side adds the commit and reveal periods on top.

Check you may legally hold both, before anything else. A jurisdiction rule removes a leg entirely, and it is written in a document you can read in two minutes: why a venue is unavailable where you are and what you have to prove to trade name where each venue's version lives. A filed contract can also bar you by occupation, however ordinary your jurisdiction.

Plan both exits before either entry. The funding rail you choose on a cash venue determines the exit rail, and the chain you deposit on determines where the stablecoin can go. A position you cannot unwind on both venues is one position and a liability, not a pair.

Price the difference in the disaster cases, not just in the fees. Last fair market price, a 50-50 split and a refund of what you paid are three different outcomes, and the leg that pays a refund of cost does not fund the leg that paid out in full. That asymmetry is the risk the gap is largely made of, along with the risk that the two rule texts diverge on the day.

Measure the gap rather than taking it from a screenshot. A quote is not a fill, and depth decides what the second leg actually costs — where liquidity comes from covers the part of the price that no schedule prints. The catalogue's cross-venue tooling is built for exactly this measurement: PMXT puts several venues behind one client shape, Adjacent publishes reference rates across venues, Polyrama and Synthesis show two venues in one screen, and Predexon sells the tick-level book history that answers whether a gap you saw was ever there in size.

Know what this page was read from. Every figure above comes from the documents cited, read on 21 September 2026: a CFTC-hosted product filing, two venues' own documentation, an oracle's protocol description and a stablecoin issuer's own page. Every Kalshi statement here is read from its Regulation 40.2(a) filing on the Commission's site rather than from the venue's own pages, which is why no Kalshi fee figure appears above; the fee guide carries those, dated to the schedule they were read from. Fee schedules, terms of service and contract terms in this sector are all amended by notice, so check the version before you act on a comparison — and the venue cards in market data APIs carry the date this catalogue last read each one.