When Large Sports Bets Land on Polymarket: Early Money Loses, Late Money Breaks Even, Graded Wallets Bet Live

Ask a sports bettor how they did and they will tell you their record. Ask a professional and they will tell you their closing line value: the difference between the price they got and the price the market closed at. Timing is the whole of that number. Bet early and you get a soft line and a wide spread. Bet at the close and you get the market's best estimate and nothing more.

Polymarket sports markets add a third phase. The book does not close at kickoff. It trades through the game, and by the second half the price on a team that is ahead looks nothing like the price before the game. Whether that live price is fair, and whether the people hitting it are the same people who bet before kickoff, is what this study measures.

The sample is every buy of $1,000 or more that 0xinsider recorded on a Polymarket sports market between April 2 to September 11, 2026, on a market that settled after the trade, at 2 to 98 cents, where Polymarket published a start time for the game. That is 396,830 buys by 13,674 wallets across 33,497 settled markets, carrying $7.89 billion. It is the calibration study's sample less the 15,000 buys on markets with no kickoff on record.

Each buy is placed in one of eight buckets by hours to kickoff: more than seven days out, one to seven days, six to 24 hours, one to six hours, the last hour, and then the first hour of play, the second hour, and anything later. Kickoff is the provider's scheduled start; a delayed start is not modeled, so a buy at scheduled kickoff plus ten minutes during a rain delay counts as in-play.

Edge and dollar return are the same measures as the calibration study: win rate minus price paid, in points, and stake-weighted return held to settlement before fees. Intervals resample markets, 5,000 draws.

48.6% of the buys and 47.7% of the dollars landed after the game had started. The last hour before kickoff took 22.8% of the buys and the first hour of play 22.4%, so four in ten large sports bets on Polymarket land in the 120 minutes around the opening whistle. Only 12.6% land more than six hours before the game. A tenth of one percent land more than a week out.

The bets get bigger as kickoff approaches. Buys placed a week or more out averaged $11,020. One to seven days out, $16,088. Six to 24 hours, $17,434. One to six hours, $19,493. The last hour, $22,468. In-play the average drops back to $17,464 in the first hour and climbs to $23,496 for buys more than two hours into play, the largest of any bucket, on games that have gone long or gone live in a second market.

A sportsbook sees the same curve from the other side: handle is thin when the line opens and floods in the hour before the game. The difference is that Polymarket's curve does not end at kickoff.

Buys placed one to seven days before kickoff won 56.5% of the time at an average price of 59.7 cents: minus 3.21 points, and the 95% interval, minus 5.09 to minus 1.35, clears zero. The 515 buys placed more than a week out came in at minus 5.55 points, on an interval, minus 11.54 to plus 0.17, that just reaches zero on a small sample. Buys placed six to 24 hours out came in at minus 0.95, with an interval that ends at zero.

From there the loss disappears. One to six hours out, minus 0.34. The last hour, plus 0.16. The first hour of play, plus 0.46. The second hour, plus 0.57. Later than that, plus 0.11. Every one of those intervals straddles zero. From six hours before kickoff to the final whistle, a large buyer on a Polymarket sports market paid what the result was worth.

Early money loses for the same reason it loses at a sportsbook. An early book is thin: the mean quoted spread on buys placed more than a week out was 18 cents, against about one cent on the day. The price has not yet absorbed the lineup, the weather or the market's own second opinion. And the buyer who is willing to put $16,000 on a game five days out is not a random draw from all bettors. In this sample that buyer was wrong more often than the price said.

Before kickoff most large buys are near a coin flip. In the last hour before the game 55.1% of buys were between 40 and 60 cents and 9.5% were at 80 cents or more. In the first hour of play the 40-to-60 share falls to 35.9% and the 80-plus share rises to 21.6%. In the second hour a third of all large buys are at 80 cents or more: a team is ahead, and the money is on it.

Those live favorites calibrate. In-play buys at 70 cents and up paid 84.1 cents and won 84.5% of the time, plus 0.37 points and plus 1.57% on the dollar across 82,105 buys. Pre-kickoff buys at 70 and up paid 81.6 and won 80.8%, minus 0.78. In-play buys between 30 and 70 cents came in at plus 0.52 and pre-kickoff buys in the same band at minus 0.28.

In-play longshots are the one live band that lost money. Buys under 30 cents during play won 22.4% at 22.3 cents, an edge of plus 0.08 points, and still returned minus 10.4% on the dollar, because the stakes that lost were larger than the stakes that won. A team that is behind is cheap for a reason, and the buyers who paid up for it paid the most.

Cricket is bet during the match: 89.1% of its large buys landed in-play. MMA, 73.4%. Tennis, 73.0%. Esports, 66.0%. At the other end, soccer is a pre-kickoff sport at 36.2% in-play, hockey 30.9%, the WNBA 27.3%. The NBA is split, 45.2%, and baseball 38.7%.

The split changes the sport's calibration. Tennis buys before the first serve came in at minus 3.21 points across 12,845 buys, the worst pre-kickoff figure of any large sport, and tennis buys during the match came in at plus 0.39 across 34,790. MMA buys before the first bell came in at minus 10.36 points on 1,419 buys, most of it two upsets, and in-play at minus 4.03. Esports pre-kickoff minus 0.80, in-play plus 0.55. The NBA minus 0.25 and plus 0.31. Soccer, the one sport positive in both phases, plus 0.39 and plus 0.82.

In every sport with both phases, the in-play figure is better for the buyer than the pre-kickoff figure. The live market, with the game in front of everyone, has been the fairer one.

From June 1, when grade coverage widened, each buy also carries the grade its wallet held that day. Split by cohort, the timing mix is different.

Wallets graded S, A or B placed 51.3% of their sports buys in-play, 45.2% on the day before kickoff, and 3.5% more than a day out. Wallets graded D or F placed 37.0% in-play, 59.0% on the day before kickoff, and 4.1% more than a day out. C wallets sit between at 44.7% in-play; wallets with no grade yet at 43.5%.

The poorly graded wallets are pre-game bettors. The well-graded wallets are half live bettors. Neither cohort bets early: more than a day out is under 5% of every cohort's buys.

Before kickoff, the grade barely separates anyone. In the last hour before the game S, A and B wallets came in at minus 0.42 points and D and F at minus 0.30. One to six hours out, plus 0.64 against minus 0.96. Six to 24 hours out, plus 0.66 against minus 0.30. Every pre-kickoff gap is under two points.

In the first hour of play, S, A and B wallets came in at plus 3.07 points and plus 9.59% on the dollar across 11,767 buys. D and F wallets came in at minus 3.03 points and minus 11.97% on the dollar across 7,996. Six points apart, on the same games, in the same hour. Later than two hours into play, plus 2.44 against minus 3.80. The second hour is the narrow one, plus 0.36 against minus 1.42.

This is the mechanism behind the sports grade study at 0xinsider.com/research/sharp-money-polymarket-sports, which found the cohorts within a point of each other before kickoff and four and a half points apart in-play. The first hour of a game is when the most information arrives fastest: a lineup, an injury, a red card, a first-inning collapse. A wallet that reads it right, or reads it first, is paid for the read. A wallet that reacts to the score is paying the wallet that saw it coming.

The alert pipeline stored the quoted bid and ask with each buy through July 31, 2026, so for the April-to-July subset the cost of crossing the book can be measured. The median quoted spread was exactly one cent in every timing bucket and every sport. The mean was 1.1 cents on the day before kickoff, 1.4 to 1.7 cents in-play, 2.0 cents one to seven days out, and 18.3 cents more than a week out on 289 quotes.

By sport, before kickoff, the median was one cent everywhere and the 90th percentile was one cent in soccer, the NBA, baseball and hockey and two cents in tennis, esports, MMA and the WNBA. A taker crossing a one-cent spread at 50 cents pays half a cent, 1% of the stake, plus Polymarket's sports taker fee, which is 2.5% of the stake at that price. A sportsbook's standard -110 line costs 4.55% of the stake on every bet.

The early book is the exception that explains the early loss. A buyer a week out is paying an 18-cent spread on average to hit a price nobody has sharpened yet.

There is no price path here. This study times buys against kickoff and scores them against the result; it does not follow one market's price from listing to close. Polymarket's hourly price history is thin in the hours before kickoff for most markets in this window, so an open-to-close movement study would be describing the markets that happen to have snapshots.

Kickoff is the scheduled start on the market. In-play buckets are by clock, not game state: a buy 40 minutes into a soccer match and a buy 40 minutes into a tennis match are both first-hour buys. Edge is measured against settlement, so a live buyer who sold at the next goal is scored on a result they did not wait for. Fees and slippage are ignored.

The sample is large buys 0xinsider recorded, at a $1,000 floor through July and $10,000 from August. It is not every fill on the platform, and a market can be calibrated for large buyers while retail buyers pay a different price. The grade splits start June 1 and are described in the sports grade study.

Every game on a 0xinsider sports board, 0xinsider.com/sports/soccer, 0xinsider.com/sports/nba, 0xinsider.com/sports/tennis and the rest, shows the kickoff countdown, the live score once the game starts, and the current price. The sharp money strip on each game shows which side the profitable wallets are on, and it updates through the game, which is where this study found their edge.

The whale alerts feed at 0xinsider.com/whale-alerts timestamps every large buy as it lands with the buyer's grade beside it. Watching it during a game is watching the first-hour money this study describes. Alerts on a wallet or a market send the same fill to you the moment it clears.

The pick of the day at 0xinsider.com/pick-of-the-day publishes one position a day with its entry price and its closing price, so each pick's closing line value is on the record. The guide at 0xinsider.com/learn/closing-line-value explains the measure, and 0xinsider.com/learn/line-movement-sports-betting-explained covers how to read a moving price before and during a game.

Every number on this page comes from one read-only run of a set of queries against the production database at 03:29 UTC on September 12, 2026. The query text, the raw output and the bootstrap script are committed in the 0xinsider repository under docs/research-articles/verification with the date 2026-09-12 and the word timing in the file names.

The universe is the calibration study's universe, every large-trade alert for a Polymarket buy on a sports-category market from April 2, 2026 with a settled outcome after the trade and a price between 2 and 98 cents, joined to the market's game start time. Hours to kickoff is the start time minus the trade time. The window starts on April 2 because the alert table's outcome index was defective before that day; the calibration study documents it.

Expect your counts to grow as open markets settle. The bucket shares should hold to a tenth of a point and the edges within their intervals.