Sponsored by Polymarket US. This page quotes Polymarket US's published rules. It is information, not a recommendation to trade.
The rule, sport by sport
Every line below is quoted from Polymarket US's Sports FAQs, read November 14, 2026. Where the FAQ has no sentence for a sport, the table says so rather than guessing.
| Sport | Player doesn't play | Player leaves early |
|---|---|---|
| MLB | "If the player doesn't participate at all, the Contract settles at LFMP." | "Stats accumulated up to that point count per the official box score." Already over the line: $1.00. Can no longer get there: $0.00. |
| Tennis | Before the first serve, a cancellation, walkover or withdrawal is a pre-event scenario: contracts "settle at last fair market prices as of the official announcement." ITF matches resolve at $0.50. | A retirement after the first serve, a default or a disqualification: the official result declared by the governing body decides it. |
| NFL | No player-participation sentence in the Sports FAQs. Read the contract's rules on its market page. | Same. |
| NBA | No player-participation sentence (the NBA section covers overtime). Read the market's rules. | Same. |
| NHL | No player-participation sentence (the NHL section covers overtime). Read the market's rules. | Same. |
Two general rules apply across sports. A participant who withdraws before the event sends game-level contracts (winner, spread, total) to last fair market prices. On futures and qualifiers, the withdrawn participant's contract settles at $0.00.
What "LFMP" means
LFMP is the last fair market price. Polymarket US defines it as "the prevailing fair market price on the Exchange at a specified moment in time," and adds: "It is not the last traded price at market close." The settlement price reflects LFMP at the time of the announcement, not prices that print afterward.
That is why a DNP is not a refund. You receive the fair price per contract at that moment, which can be above or below the price you paid.
What the US Rulebook says, and doesn't
The US Rulebook (2026.09.30).pdf) has no player-prop participation rule. Rule 10.3 lets the company modify a contract's specifications if an event may materially affect it, and Rule 10.4 covers review of an outcome before settlement. The participation rules come from the Sports FAQs and each market's own terms. Our Polymarket US settlement rules page quotes the rest: ties, postponements, cancellations and how outcomes are reviewed.
Combos: one leg sits
A combo is not canceled when one player doesn't play. Polymarket US says a leg that can't resolve is worth its last fair market price and stays in the combo, and the combo settles once. The mechanics are in our guide to Polymarket US combos.
How this compares with Kalshi
Kalshi doesn't refund a DNP either: a player who is ruled out, or is active and never takes a snap, settles at the last fair price Kalshi sets. The difference is where the line is published. Kalshi writes its NFL and NBA participation tests into the contract terms (one snap in the NFL, entering the game in the NBA). Polymarket US publishes its participation sentence for MLB. The full Kalshi rule is in If a player doesn't play, does Kalshi void the contract?
Where to go next
- Will It Void? checker: every platform's rule for the situation you're in.
- Polymarket US settlement rules: ties, postponed and canceled games, outcome review.
- Polymarket US, page by page: fees, the app, withdrawals and every board we track.
- New to the app? Our Polymarket US promo code page covers what to enter at sign-up.
18+ Only. Restrictions and eligibility requirements apply. Not available in all jurisdictions. Trading is risky. 100% loss can occur. See https://polymarketexchange.com/files/legal/Polymarket%20US%20Rulebook%20(2026.09.30).pdf for more information. The Polymarket US App serves as an independent software provider and affiliate of Polymarket US and Polymarket Clearing, the CFTC-regulated exchange and clearing organization.