Best Prediction Market for Arbitrage Betting in 2026: Fees, Fills and Settlement Ranked

The quick answer

Cheapest pre-game leg: Novig. No fee for maker or taker on pre-game straight trades, and $0 maker fee on every trade type.

Best for seeing depth before you trade: Kalshi. Its order book is readable through a public API with no login.

Best for posting the resting leg: Polymarket US. Makers are paid a rebate, and an immediate-or-cancel order stops a partial fill from sitting on the book.

Closest settlement match to a sportsbook: ProphetX. A voided contract returns your collateral.

Most expensive: DraftKings Predictions, at 2c per contract between 30c and 94c, charged when you open and again when you close.

What the arb leg needs from a prediction market

An arbitrage pairs two prices that together guarantee a return. In the US one side is usually a sportsbook and the other a prediction market, because the two price the same game independently.

The prediction-market leg has to leave the edge intact after fees and settle on the same facts as the book, and it has to fill at the price you saw.

How we compared

Every fee, order type and settlement rule below comes from the venue's own fee page, help center, contract terms or API documentation, opened again on 7 October 2026.

Kalshi's taker and maker coefficients come from its fee schedule effective 7 July 2026, checked 7 October, and its series-level multipliers from its public API.

What one arb leg costs, maker and taker

The same pre-game arb throughout: a sportsbook leg at decimal 2.04 (+104) and a prediction-market leg of 206 contracts at 48c. That's $100.98 at the book and $98.88 on the prediction market, $199.86 in total, paying $206.00 whichever side wins. Profit before fees is $6.14.

Taking the price is the safer way to build an arb, because the prediction-market leg fills immediately at the quoted price if the size is there. Resting it as a maker costs the same or less everywhere, and Polymarket US pays you, but the sportsbook price can move before your order fills.

The prediction markets, ranked for arbitrage

The ranking follows what the leg costs before the game. On the position above, Novig keeps all $6.14 of the edge, where a Kalshi taker on a standard sports series keeps about $2.54. On visible depth, Kalshi would rank first, and on void refunds, ProphetX.

1. Novig: zero fee before the game

Novig charges no fee to either side on a pre-game straight trade, through the app or its API. Takers pay 0.03 x price x (1 - price) per contract in-game, 0.06 on futures and 0.10 on parlays, and the maker fee is $0 on every trade type. A maker matched in-game also earns a cash credit of 50% of the taker fee collected on the other side.

Novig has take orders, which fill at once against a resting price, and make orders, which rest at a price you set in fixed increments for a duration you choose. A pre-game make order cancels automatically when the game goes live.

On a voided contract, such as a scratched player or a game never completed, Novig settles at a fair value: a time-weighted price over the 30 minutes before the news, built from outside markets with their margin removed, at least two where available, plus Novig's own bid-ask midpoint. The payout can land below your entry: Novig's own example shows a YES bought at 52c settling at 45c.

Novig runs on Ludlow Exchange, LLC, a CFTC Designated Contract Market. Its contracts page lists MLB, NFL, WNBA, MLS, UFC, PGA and ATP and WTA series, and NBA contracts were certified on 29 September 2026. We found no public depth data for Novig, so test a fill at your size first. Its help center lists it as unavailable in Arizona, Michigan and Nevada.

Best for: the prediction-market leg of a pre-game arb.

2. Kalshi: the book you can read

Kalshi's standard taker fee is 0.07 x price x (1 - price), or $1.75 per 100 contracts at 50c, and its NFL and NBA game series also charge makers. Its API lists a multiplier per series, and its MLB game, run line and total series have run at 0.5 since 7 August 2026.

Anyone can pull Kalshi's bids and sizes for a market through its public API without logging in. Its busier markets, such as postseason MLB game winners, tended to show tight spreads with size in the thousands of contracts.

On a game that can't be settled, Kalshi resolves at the last fair market price as determined by the exchange.

Best for: sizing a position before you commit, and MLB taker legs.

3. Polymarket US: paid to rest

Polymarket US's taker coefficient has been 0.0695 since 1 October 2026, which is $1.74 per 100 contracts at 50c, and makers are paid 0.0125 x price x (1 - price). Taker volume above $250,000 in a month earns back 10% to 50% of taker fees. Polymarket US changed some fees again on 7 October 2026, so check its current schedule before relying on these figures.

Its limit orders can be good 'til canceled, expire at 12am PT or at the start of the game, or run immediate-or-cancel, which drops any unfilled part at once. For an arb, immediate-or-cancel stops a half-filled leg from resting on the book. Order-book data comes through its API with a market-data scope, and there's no public trade tape.

On a cancellation, a pre-event withdrawal or a game not completed before the contract expires, Polymarket US settles at the last fair market price at the time of the announcement.

Best for: the resting side of an arb, and traders who want order-level control.

4. ProphetX: refunds where others settle

ProphetX takes 2% of net gains per market on straight trades, so a leg that loses costs nothing. It offers market and limit orders, and live orders pass through a 2-second delay.

Its rules void contracts and return collateral when an MLB game is postponed, the same result you'd get at a sportsbook. Paired with a book, a ProphetX leg on a postponed game comes back to you as cash on both sides.

Best for: arbs on events where cancellation is a live risk.

5. DraftKings Predictions: the costliest leg

DraftKings' own fee disclosure lists $0.02 per contract per side for prices from 30c to 94c, so an arb leg pays to open and pays again if you close it before settlement. It's available in a limited set of states, and its sports menu and settlement terms can differ from the other venues here, so read them in the app before you pair a leg there.

Best for: bettors whose only prediction-market account is with DraftKings.

Where the venues differ on settlement

A sportsbook such as DraftKings voids a bet and returns the stake, and ProphetX does the same on a postponed MLB game. Novig, Kalshi and Polymarket US settle the contract at a fair price instead, which can sit above or below what you paid.

So a scratched player or a cancelled game can refund the book leg and mark the prediction-market leg to market. With Novig's fair-value example, a 1,000-contract YES leg bought at 52c and settled at 45c loses $70 while the book returns its stake.

For a postponed MLB game, Kalshi waits 48 hours, Novig 48 hours or 45 days in the postseason, and Polymarket US until the contract expires, typically two weeks, while DraftKings Sportsbook and ProphetX void a game that doesn't start on its scheduled day.

What to look for

Fee on the leg you take: pre-game straights on Novig carry none.

Maker economics: Polymarket US pays makers, Novig charges them nothing, and some Kalshi series charge both sides.

Void rule: a fair-value settlement against a sportsbook refund leaves one leg open.

Visible depth: Kalshi's book is public; test fills elsewhere.

Order controls: an immediate-or-cancel or a timed make order keeps a partial fill from resting.

Your state: sports contracts are restricted or litigated in several states, and the list changes with court rulings.

Prediction market arbitrage FAQ

What is the best prediction market for arbitrage betting?

Novig for a pre-game leg, since it charges no fee to either side of a pre-game straight trade and no maker fee anywhere. Kalshi is the one to use when you need to see the order book, Polymarket US when you'd rather be paid to rest, and ProphetX when you want a void refunded.

What happens to a prediction market contract if the game is cancelled?

Novig, Kalshi and Polymarket US settle it at a fair or last fair market price, which can differ from your entry price. ProphetX voids an MLB game that doesn't start on its scheduled day and returns collateral.

Is Polymarket the same as Polymarket US?

No. Polymarket US is the CFTC-regulated American venue run by QCX LLC, with its own fee schedule.

Sources

Checked 7 October 2026 except where noted.

Novig fee schedule: support.novig.com/en/articles/16195057-fees-on-novig

Novig Fair Value Settlement: support.novig.com/en/articles/16163706-what-is-fair-value-settlement-fvs

Novig make and take orders, valid make-order prices, Maker Credit Program, contracts list and eligibility: support.novig.com articles 10715726, 15554753, 16116780, 16083642 and 16194031

Novig contract terms and certifications: ludlowexchange.com/filings

Kalshi series fee settings, order books and contract terms: Kalshi public API (series, fee changes, order books); BASEBALLGAMEWIN contract terms

Kalshi fee schedule: kalshi.com/docs/kalshi-fee-schedule.pdf (effective 7 July 2026)

Polymarket US fee schedule, order types, market data and sports FAQ: docs.polymarket.us

ProphetX Understanding Fees, order types, live orders and Baseball Rules: ProphetX help center, updated 19 August, 15 June and 6 October 2026

DraftKings Predictions fee disclosure: myaccount.draftkings.com/documents/fee-disclosure?product=predict (standard pricing)