Cash out betting explained: when to sell a sports bet on Polymarket

A sportsbook's cash-out offer is a number the book computes and never explains. You backed a team at +150 for $100, they lead at halftime, and the book offers $180 now against $250 if they hold on. Whether $180 is fair depends on how likely the team is to win from here, and the book is the only party that has put a number on that.

On Polymarket the offer is the best bid, set by other traders, and every exit is a public trade that can be checked against how the game ended. The chart above does that by sport. No split has a margin you could call hidden: the cost of an exit is the spread and the fee, and you see both before you sell. The sport splits are not resampled, so treat the gaps between them as noise.

On Polymarket a bet is a position: a number of shares, each paying $1 if the outcome happens. Cashing out is selling shares. A market sell takes the best bids on the order book, so the price is whatever buyers are paying right now. A limit sell rests at a price you choose and fills if a buyer comes to it. Every sale is public, with the wallet and the price on the chain.

Near even money the fee costs more than the spread. A taker sale pays Polymarket's sports fee from the proceeds: 1.25¢ a share at 50¢ and 0.45¢ at 90¢ on most sports (NFL and college football games carry 0.03 and NBA games no fee, as of October 21, 2026). A limit sell that rests on the book and fills is a maker order and pays nothing. The fees guide has the formula.

Holding a share is worth your probability of the outcome times $1. Selling it is worth the bid, less the fee if you take the bid. The whole decision: sell when the price you can get is above the probability you believe, hold when it is below. How much you paid, how much you are up and how nervous the game makes you are not in the comparison.

Take a share bid at 60¢. If you think the outcome is 55% likely, holding is worth 55¢ and selling is worth about 58.8¢ after the fee, so you sell. If you think it is 70% likely, holding is worth 70¢ and you hold. At 59% the two are within a fraction of a cent, and a limit sell at 61¢ with no fee is the better exit if a buyer comes.

The chart above draws that comparison across your probability, for a 60¢ bid. It is arithmetic, not data.

0xinsider checked every large sell it recorded on a Polymarket sports market from April 2 to September 13, 2026 against how the market settled yes or no: 38,601 sells, $781.8 million of cash, two thirds of them during the game. The smallest was about $3,000 until July 2, 2026, and after that 96% were $10,000 or more, so this is how large traders exit, not every exit.

The outcomes sellers let go of won 64.9% of the time at an average exit price of 64.1¢. The exit edge, the price minus how often the outcome won, came to minus 0.87 points with a market-resampled interval from minus 2.15 to plus 0.33. The cash-out study has the method.

Exits were fair. Buyers in the same markets paid 60.6¢ and won 60.9%, and sellers did no worse than a point. Every price band's interval includes zero. On Polymarket, the cash-out price carries no hidden margin on average; the only cost is the spread and the fee.

The worst-looking exits in the study were longshots sold at 10¢ to 20¢: 1,575 sells at 15.2¢ on outcomes that won 25.7% of the time, on an interval from minus 34.25 to plus 6.60 that still includes zero. One market drives it. Spain drew 236 large sells at 15.3¢ and then won the World Cup.

Leave Spain out and the other 2,045 sells under 20¢ went at 12.1¢ on outcomes that won 9.5% of the time, so those sellers got more than the longshots were worth.

That fits what longshots are on Polymarket: the most overpriced thing to buy, which makes them fair or better to sell. The favorite-longshot study found buys under 10¢ returning 44 cents on the dollar, weighted by stake. If you hold a longshot you no longer believe in, the price is usually on your side when you sell. Occasionally the one you sell is Spain.

Before kickoff, the two ends of the price range went opposite ways. Sellers of underdogs, 144 sells at 14.1¢, let go of outcomes that won 26.4% of the time: minus 12.29 points, with an interval from minus 23.80 to minus 1.60. That is the one result here that clears zero, on 96 markets. An underdog you still believe in is a poor thing to dump cheap before the game.

Sellers of heavy favorites, 835 sells at 87.2¢, let go of outcomes that won 81.4%: plus 5.81 points, with an interval from minus 0.28 to plus 12.45 that reaches zero. A big favorite is at best a fair sale. An earlier version of this guide said both results cleared zero; with refunded markets left out of the count, only the underdog result does.

Most sells at 60¢ and up came during the game, and taking the money on a winning bet cost almost nothing beyond the trade. Large in-play sellers at 80¢ and up, 9,991 of them at an average of 89.2¢, let go of outcomes that won 89.5% of the time: within a point of fair, on an interval from minus 1.88 to plus 1.26.

The trade is cheap at high prices. Selling at 90¢ as a taker gives up 0.45¢ a share to the fee, and the spread is usually a cent. Selling at 60¢ gives up 1.20¢ to the fee. A limit sell a cent above the bid pays no fee, at the risk that no buyer comes before the price moves.

Polymarket lets you sell any part of a position, and large sellers mostly sold in one go: 82.9% of the positions that cashed out took a single large sale. A smaller sale is never recorded, so some of those traders may have trimmed in smaller pieces first.

Selling part of a position is the simplest way to cut risk without abandoning a view. If you bought 1,000 shares at 50¢ and they now trade at 80¢, selling 625 of them returns your $500 stake and leaves 375 shares riding. From there the worst case is breaking even, before fees.

Hedging is buying the other side. On a binary Polymarket market, buying No on your outcome at 20¢ locks in the same 80¢ as selling Yes at 80¢, because one Yes and one No pay exactly $1 whatever happens. Selling is usually cleaner: it frees the cash now instead of at settlement. On a soccer match, the other side of a team to win is No on that team, which covers the draw and the other team.

0xinsider grades every Polymarket wallet from S to F on its settled record. From June 2026, graded as of each sale (re-measured October 7, 2026), sells by wallets graded S, A or B came in 2.10 points below fair across 2,574 sells, and sells by wallets graded D or F 0.15 below across 4,888, with no split's interval excluding zero. The graded wallets do not exit at better prices.

What separates them is what they buy and when. The sharp money study found S, A and B wallets 2.45 points ahead of D and F wallets on buys made during the game, and level with them before it. A good trader's work is done at entry. The exit is routine, and on Polymarket it is priced fairly for everyone.

The feed records far fewer large sells than large buys. From September 11 to October 10, 2026, 495 of the 11,768 large sports trades 0xinsider recorded were sells. Tennis had the most, and 94.7% of its large sells came during play. A run of large sells on one side of a live game is rare enough to notice, and it shows the market moving away from that side.

The large-trade feed marks each trade BUY or SELL with the price, the size and the grade of the wallet: live with Pro, 24 hours behind with an account, and a day old on the public feed without signing in. On an event page, Top holders, a Pro section, lists who still holds each outcome, and a wallet's profile shows its open and closed positions beside its settled record.