Best Betting Platforms for NBA Arbitrage in 2026: Fees, Coverage and the Overtime Question

The quick answer

Cheapest NBA leg to take before tip-off: Novig. No fee for maker or taker on pre-game straight trades.

Visible depth: Kalshi. Its public order books show spread and size before you trade.

Best if you post rather than take: Polymarket US. Makers collect a rebate.

Closest settlement match to a sportsbook: ProphetX. A scratched player's contract is voided and collateral returned, the same as at DraftKings' sportsbook.

Limited footprint: DraftKings Predictions. It's available in a limited set of states, so check the app for yours.

What breaks NBA arbs: Kalshi's second-half and fourth-quarter markets exclude overtime, a scratched player is refunded at DraftKings' sportsbook but settled at a fair price on Novig and Kalshi, and DraftKings' fourth-quarter markets include overtime while Novig's and Kalshi's exclude it.

For the prediction-market leg of a pre-game NBA arb, Novig is the cheapest place to take a price, because it charges nothing on pre-game straight trades. On a $200 position that keeps all $7.00 of a 3.5% edge, where a Kalshi or Polymarket US taker gives back more than $3.50 of it. Kalshi publishes its order-book depth, Polymarket US pays makers to rest orders, and ProphetX settles a late scratch the way DraftKings' sportsbook does.

What NBA arbitrage is

You back both sides of an NBA market on two venues at prices that together guarantee a return, whichever team wins. Many US positions pair a sportsbook leg with a prediction-market leg, since the two price the same game independently.

The edge is usually small, so two things decide whether you keep it: the fee on the prediction-market leg, and whether both venues settle the game on the same facts.

How we checked

This covers venues a US bettor can open and get an NBA position filled on. Fees and settlement rules come from each platform's own schedule, contract terms or house rules, and depth comes from Kalshi's public market data.

Except where noted, everything below was checked on 7 October 2026. Kalshi's fee schedule is the version effective 7 July 2026. DraftKings Predictions' fee comes from DraftKings' own fee disclosure. The regular season opens 20 October 2026.

The platforms for NBA arbitrage

Novig: the cheapest pre-game leg

Novig charges no fee to either side on a pre-game straight trade. In-game, takers pay 0.03 x price x (1 - price) per contract, which is 75c per 100 contracts at even money, and makers pay nothing on any trade type. Makers matched in-game also earn a cash credit of 50% of the taker fee collected from the other side.

Novig runs on Ludlow Exchange, LLC, a CFTC Designated Contract Market. Its NBA winner, spread, total and player prop contracts were certified with the CFTC on 29 September 2026, three weeks before the regular season.

Depth on a new NBA menu is hard to judge from outside, so test a fill at your size before you build a position around it.

Best for: the prediction-market leg of a pre-game arb on sides, totals and props.

Kalshi: depth you can check

Kalshi lists NBA game winners, spreads, totals, quarters, halves and player props, and its order books are public. Same-day games tended to show tighter spreads and more size than games further out.

Kalshi's standard taker fee is $1.75 per 100 contracts at 50c, and its NBA game, spread and total series charge the resting side a maker fee as well.

Best for: filling size close to tip-off.

Polymarket US: paid to post

Polymarket US raised its taker coefficient to 0.0695 on 1 October 2026, which is $1.74 per 100 contracts at 50c. Makers are paid $0.31 per 100 at the same price. If your arb leg can rest and wait, rest it here. Polymarket US changed some fees again on 7 October 2026, so check its current schedule before relying on these figures.

Best for: the resting side of an arb.

ProphetX: settles a scratch the way DraftKings does

ProphetX takes 2% of net gains per market on straight trades, so a position held to settlement pays only on the winning leg. Its basketball rules include overtime in full-game and second-half contracts. If a listed player doesn't participate, contracts on that player are voided and collateral is returned. That matches DraftKings' sportsbook, which makes ProphetX the cleanest second leg for a player-prop arb.

Best for: player props paired with a sportsbook.

DraftKings Predictions: limited states

DraftKings Predictions charges a combined 2c per contract under its standard pricing. It's available in a limited set of states, and its NBA menu can differ from the other venues here, so check the app for what it lists where you are.

Best for: bettors where it's available who already hold a DraftKings login.

The sportsbook leg, and venues you can't use

A sportsbook such as FanDuel, DraftKings or BetMGM can supply the other leg. Its price carries the vig, so a scanner's arb percentage already includes it. DraftKings' house rules include overtime in every basketball market except three-way moneylines, fourth-quarter player points and fourth-quarter/moneyline markets.

Many international arbitrage guides are built around offshore books and exchanges that don't take US customers.

What an NBA arb keeps after fees

Say a pre-game arb pairs a sportsbook leg at decimal 2.10 (+110) with a prediction-market leg at 49c. Stake $98.57 at the book and buy 207 contracts for $101.43. Total outlay is $200.00, and either result pays $207.00, a $7.00 profit before fees.

Where NBA arbs break

The overtime question

Full-game moneylines include overtime at every venue checked, and so do full-game spreads and totals wherever we read the terms.

On segment markets, Kalshi's terms say a quarter or half, the fourth quarter and the second half included, excludes overtime unless the title says otherwise. Novig, ProphetX and DraftKings all count overtime in second-half markets. DraftKings also counts it in fourth-quarter markets, where Novig and Kalshi don't.

Say you take Team A to win the second half on Kalshi and Team B second half at DraftKings, and the second half finishes tied in regulation before Team A wins in overtime. Kalshi needs Team A to outscore Team B in the second half itself, so that leg resolves No. DraftKings counts overtime, so Team B's ticket loses as well, and you're out both stakes.

Late scratches

NBA injury news lands close to tip-off. At DraftKings and ProphetX, a player who doesn't appear in the game gets a void and your stake back. Kalshi settles a pre-game withdrawal at a last fair price of its choosing, while Novig voids the contract and settles it at a fair value taken from the 30 minutes of trading before the news broke.

So a DraftKings-against-Novig prop arb on a scratched player refunds one leg and marks the other to market. In Novig's own example, a YES bought at 52c settled at 45c, a 7c loss per contract.

Season timing

Prediction markets can list preseason games too, so the scratch rules above can apply before the regular season starts on 20 October.

What to look for

Segment rules: read how both venues treat overtime before arbing a half or quarter.

Scratch rules: pair a book with ProphetX for props, or price in a fair-value settlement on Novig or Kalshi.

Fee timing: Novig's zero-fee window closes at tip-off.

Depth: test fills where you can't see the book.

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

NBA arbitrage FAQ

What is the best app for NBA arbitrage betting?

For the prediction-market leg of a pre-game arb, Novig, which charges no fee on either side of a straight trade. Kalshi publishes its order-book depth and suits filling size close to tip-off, Polymarket US pays makers a rebate, and ProphetX matches DraftKings' sportsbook settlement on scratched players.

Does overtime count in NBA bets?

Full-game moneylines, spreads and totals include overtime at every venue whose terms we read. Second-half and fourth-quarter markets differ by venue, so check both sides of a segment arb.

What happens to an NBA prop arb if the player doesn't play?

DraftKings' sportsbook and ProphetX void the bet and return the stake; check your own book's rules. Novig and Kalshi settle at a fair price, which can be above or below what you paid.

Is NBA arbitrage risk-free?

No. Settlement differences between venues can lose both legs, and fees can take more than half of a small edge.

When does the 2026-27 NBA season start?

The regular season opens on 20 October 2026.

Sources

All 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 Maker Credit Program: support.novig.com/en/articles/16116780-maker-credit-program

Novig NBA contract certifications and terms: ludlowexchange.com/filings (NBA Winner, Spread, Total and Prop, certified 29 September 2026)

Kalshi NBA series fee types and contract terms: Kalshi public API (KXNBAGAME, KXNBASPREAD, KXNBATOTAL); Kalshi BASKETBALLGAMEWIN, BASKETBALLTOTALS and BASKETBALLENTITYSTAT contract terms

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

Polymarket US fee schedule: docs.polymarket.us/fees (effective 1 October 2026); basketball contract AADCBK, polymarketexchange.com/files/products

ProphetX Basketball Rules and Understanding Fees: ProphetX help center, updated 4 August and 19 August 2026

DraftKings Predictions fee disclosure: myaccount.draftkings.com/documents/fee-disclosure?product=predict (Predictions standard pricing), opened 7 October 2026

DraftKings Sportsbook house rules, basketball section: Massachusetts Gaming Commission filing, version 8.18.25

2026-27 NBA opening night: Fox Sports