Sportsbooks limit winning bettors because a customer who keeps winning is, from the book's side, adverse selection: someone who knows more than the price. A lower maximum stake is the cheapest response. Wikipedia's summary of the research says bookmakers usually detect arbitrage bettors quickly and that their maximum wagers are often cut heavily, sometimes until betting is no longer viable.
We compared that picture with 30 days of our own esports data (Sep 6 – Oct 6, 2026): about 4.87 million arbitrage opportunities across 27 books: 25 sportsbooks and crypto sportsbooks plus the Polymarket and Kalshi exchanges. Three results stand out. Esports arbs are much larger than in the football study that is usually quoted: the median best ROI was 2.89% and only 13.75% of arbs were below 1%. A rule of thumb we have used ourselves, that a 10%+ arb is a stale line, is not supported by the lifetimes. And arbs with an exchange leg live longer, which is where limits matter least.
Why bookmakers limit accounts
A sportsbook sets a price from a model, a feed and the bets it receives, and charges a margin on top. Third-party guides to Pinnacle commonly put a standard sportsbook margin at 5–7% and Pinnacle's own at 2–3%. A bettor who beats that margin repeatedly is telling the book its price is wrong. Cutting the maximum stake costs the book nothing and stops the leak.
Arbitrage bettors are the clearest case, because they win by definition: the implied probabilities of the best prices add up to less than 1 (surebet). According to the Wikipedia article on arbitrage betting, which cites a 2016 Yale senior essay by Avery Schwartz on the European soccer market, the practice is usually detected quickly. In the past it could mean half of an arbitrage bet being cancelled or the account being closed. Our own explainers cover the mechanics: betting limits and why bookmakers limit accounts.
There is an opposite model. A guide to Pinnacle sports betting (by Pinnacle Odds Dropper) describes a "winners welcome" policy: sharp action is used to turn opening lines into accurate closing lines. As that guide states it, limits open at about 25% of the maximum and scale up towards the start of the event. That is a claim of the source, not something we measured. Our reading: a book that earns from a low margin and from price accuracy has a reason to keep winners. A book that earns from a high margin on recreational flow has a reason to remove them.
What the research says about arbitrage size
Franck, Verbeek and Nüesch studied arbitrage in football betting (working paper 2009, published in Economica, vol. 80, issue 318, 2013). They looked at 5,478 matches in the top five European leagues over three seasons, with prices from eight bookmakers and one betting exchange. They found only 10 arbitrage opportunities between bookmakers, but 1,450 cases where a bookmaker bet combined with an exchange bet gave a guaranteed profit. The authors link this to the two kinds of market differing in informational efficiency.
Wikipedia cites the same study for a second number: 98% of arbitrage opportunities return less than 1.2%. Two things follow. Arbitrage in that setting is a thin-margin activity, and the opportunities that exist are mostly between a bookmaker and an exchange rather than between two bookmakers.
Our distribution: esports arbs are bigger
Our median ROI over the 30 days was 2.89%, where ROI is the best value an arb reached during its life. The history holds arbs with a best ROI from 0.5% to 15.0%. Only 13.75% were below 1%, and 35.78% below 2%, so the share below 1.2% is somewhere between those two numbers, nowhere near 98%.
| ROI bucket | Arbs | Share | Median life | One snapshot | ≥10 s | ≥60 s | Live share |
|---|---|---|---|---|---|---|---|
| <1% | 669,966 | 13.75% | 2.11 s | 34.9% | 29.6% | 7.2% | 64.8% |
| 1–2% | 1,073,400 | 22.03% | 2.06 s | 37.3% | 26.7% | 5.9% | 72.1% |
| 2–3% | 757,546 | 15.55% | 2.04 s | 39.5% | 22.5% | 4.6% | 79.6% |
| 3–5% | 940,016 | 19.30% | 2.02 s | 42.4% | 20.0% | 3.4% | 88.0% |
| 5–10% | 1,058,490 | 21.73% | 2.02 s | 42.8% | 19.2% | 2.8% | 91.3% |
| ≥10% | 372,057 | 7.64% | 2.03 s | 41.8% | 19.8% | 2.8% | 92.9% |
"One snapshot" means the arb was seen once and was gone by the next scan, which runs about every 2 seconds. This is not a like-for-like comparison with the football study. It is a different sport and a later period, 27 books instead of eight bookmakers and one exchange, and our ROI is the best value reached during an arb's life, which is never lower than a single snapshot would show. Esports lines move fast and books price many small markets (handicaps, totals, rounds). The median esports arb here, at 2.89%, is more than twice the 1.2% line the football study drew.
Are 10%+ arbs a gift or a stale line?
Our own hypothesis going in was that a very high ROI is more often a stale quote than a bookmaker's mistake. If so, 10%+ arbs should be shorter-lived than small ones. The all-arbs table seems to agree: arbs lasting 60 s or more fall from 7.2% in the lowest bucket to 2.8% in the top two, and the share seen in a single snapshot rises from 34.9% to 41.8%.
But look at the last column. The live share grows from 64.8% to 92.9% as ROI rises, and live arbs are short in every bucket: across the whole window 1.4% of live arbs lasted 60 s or more, against 17.7% of prematch arbs. So the first comparison mixes two things. Splitting out live arbs removes the mix:
| ROI bucket | Live arbs | Median life | One snapshot | ≥60 s |
|---|---|---|---|---|
| <1% | 433,104 | 2.00 s | 49.6% | 1.2% |
| 1–2% | 772,447 | 2.00 s | 49.1% | 1.2% |
| 2–3% | 602,083 | 2.01 s | 47.8% | 1.3% |
| 3–5% | 825,370 | 2.01 s | 47.1% | 1.4% |
| 5–10% | 963,998 | 2.01 s | 46.2% | 1.5% |
| ≥10% | 344,845 | 2.02 s | 44.4% | 1.9% |
Inside live play the buckets look the same. The median life is 2.00–2.02 s everywhere, and the 10%+ bucket is, if anything, slightly better: 44.4% single-snapshot arbs against 49.6% in the lowest bucket, and 1.9% lasting a minute against 1.2%. Arbs with an exchange leg are 14.1–17.8% of every bucket, so exchanges do not explain the pattern either.
We have not re-weighted the all-arbs table to an equal live share, and we did not break out prematch by bucket. So we cannot say that high ROI is worse, and we cannot say it is better. What we can say is that the stale-line rule is not supported by arb lifetimes: in live play, big arbs live as long as small ones. Lifetime is only a proxy; the direct check for a stale quote is its age. That is why Dozor shows the age of every quote next to the ROI.
Where limits matter less: exchanges
Polymarket and Kalshi are exchanges. Prices come from other traders, not from a bookmaker's model, so there is no book to protect from winners. That is our reading; check each venue's terms and your jurisdiction. The data show how often they matter:
- Frequency. 15.9% of arbs had a Polymarket or Kalshi leg: 642,253 with Polymarket and 138,017 with Kalshi, over the same 30 days.
- Lifetime. In live play, 23.9% of arbs with an exchange leg lasted 10 s or more, against 14.4% for sportsbook-only arbs. For 60 s or more it was 2.9% against 1.2%, so exchange arbs are 1.7× and 2.4× as likely to survive (more in how long surebets last).
- By venue. The median lifetime was 4.1 s for Polymarket and 4.0 s for Kalshi, against 2.0 s for all arbs. Arbs lasting 60 s or more were 8.3% of Polymarket arbs, 6.9% of Kalshi arbs and 4.5% overall.
- ROI. In prematch the median ROI of arbs with an exchange leg was 2.30%, against 1.54% for sportsbook-only arbs.
This fits the football study above: the more reliable gaps are between a bookmaker and an exchange. A caveat applies. An exchange leg is limited by the depth of its order book at the quoted price, and fees are part of the ROI. See prediction markets vs sportsbooks and how to arbitrage Polymarket and Kalshi.
What this means in practice
- Do not rank arbs by ROI alone. In our data a 10%+ arb in live play lived as long as a 1% one, which does not make it safe either. Check the age of both quotes and whether the match is live before acting.
- Plan for limits as a cost. A sportsbook leg can shrink or disappear. Use more than one book, and read each book's terms. Multiple accounts and other ways around a book's rules get accounts closed, and we do not suggest them.
- Use the legs that stay open longer. Exchange legs lived longer in our data. Filter by book and minimum ROI so the screen shows only what you can act on: Dozor's alerts take a minimum ROI, disciplines, books and live or prematch.
FAQ
Why do bookmakers limit accounts?
Because a consistently winning account signals that the price is wrong, which is adverse selection. Cutting the maximum stake is the cheapest fix. Pinnacle is described as following the opposite policy, "winners welcome", by third-party guides.
Do sportsbooks limit arbitrage bettors?
Per Wikipedia's article on arbitrage betting, yes: maximum wagers are often reduced heavily when the book detects the pattern. Exchanges such as Polymarket and Kalshi are a different model, since there is no bookmaker taking the other side.
How big are arbitrage opportunities?
A football study cited by Wikipedia found 98% below 1.2% ROI. In our esports data (Sep 6 – Oct 6, 2026) the median best ROI was 2.89%: 13.75% of arbs were below 1%, 22.03% between 1% and 2%, and 7.64% at 10% or more. Different sport, period and method, so it is not a like-for-like comparison.
Are high-ROI arbs stale lines?
Not by lifetime. In live play the 10%+ bucket had a median life of 2.02 s against 2.00 s for the lowest bucket, and 1.9% of its arbs lasted 60 s or more against 1.2%. Exchange legs are the ones that last: 23.9% of live arbs with one lasted 10 s or more, against 14.4% for sportsbook-only arbs.
Try it
Dozor scans 25 sportsbooks plus Polymarket and Kalshi for esports arbs, with the ROI, the age of every quote and a direct link per leg, so you can filter by book and ROI and see exchange legs on the same screen. Free plan: no card and no time limit, every arb with ROI up to 1% in full and without delay; above that you see the count and the best ROI. Open Dozor.
Data from Dozor (Sep 6 – Oct 6, 2026), an esports arbitrage scanner covering 25 sportsbooks plus Polymarket and Kalshi. Dozor is an information tool, not a bookmaker. 18+. Betting involves risk of loss; sportsbooks may restrict arbitrage accounts.
