Observed market data
Did the Best-Available 1X2 Book Improve by Kick-Off?
Our earlier opening-versus-closing study looked at Bet365 and market-average prices. This companion analysis asks a different question: what happened to the book when we combined the maximum listed home, draw and away prices at each snapshot?
What we compared
For each match, Football-Data.co.uk provides maximum opening and closing prices across its recorded bookmaker set. We combined the maximum home, draw and away price at each snapshot and converted those prices to implied probabilities.
Best-available book = (1 ÷ maximum home odds + 1 ÷ maximum draw odds + 1 ÷ maximum away odds) × 100
Change = closing book − opening book
A positive change means the combined book was higher at the closing snapshot; a negative change means it was lower. As with our other cross-bookmaker calculations, the three maximum prices need not come from one bookmaker.
The 10-match comparison
| Match | Opening best book | Closing best book | Change |
|---|---|---|---|
| Liverpool v Bournemouth | 100.54% | 102.01% | +1.47 pp |
| Aston Villa v Newcastle | 100.94% | 101.65% | +0.71 pp |
| Brighton v Fulham | 102.95% | 102.87% | -0.08 pp |
| Sunderland v West Ham | 102.82% | 101.76% | -1.06 pp |
| Tottenham v Burnley | 101.95% | 103.07% | +1.12 pp |
| Wolves v Man City | 100.90% | 101.15% | +0.25 pp |
| Chelsea v Crystal Palace | 102.15% | 101.39% | -0.76 pp |
| Nott'm Forest v Brentford | 102.19% | 102.71% | +0.52 pp |
| Man United v Arsenal | 101.61% | 102.08% | +0.47 pp |
| Leeds v Everton | 101.36% | 102.27% | +0.91 pp |
The direction was mixed. Sunderland v West Ham showed the largest fall, from 102.82% to 101.76%. Liverpool v Bournemouth showed the largest rise, from 100.54% to 102.01%.
Summary statistics
Seven matches moved to a higher best-available book and three moved lower. The average change was about +0.36 percentage points. That contrasts with the market-average prices in the same dataset, where the average book changed only slightly from 105.56% to 105.47%.
Why can the best-price book move differently?
The market-average book and the cross-bookmaker best-price book answer different questions. An average price reflects the centre of the bookmaker set. A maximum price depends on the strongest recorded quote for each individual outcome. If one especially competitive quote disappears or another improves, the maximum-price calculation can move even when the broader market average barely changes.
This is also why the result should not be interpreted as evidence that “odds get worse before kick-off” in general. The sample is only 10 matches, and the maximum-price benchmark is particularly sensitive to which bookmakers and quotes are present in the source.
Worked example: Chelsea v Crystal Palace
The best-available opening prices were 1.64, 4.35 and 5.50, producing a 102.15% book. The maximum closing prices were 1.88, 3.85 and 4.50, producing 101.39%.
Opening best-available book = 102.15%
Closing best-available book = 101.39%
Change = −0.76 percentage points
The individual outcome prices moved in different directions. That is precisely why book percentage is useful: it summarises the combined implied probability rather than focusing on one selection.
Limitations
- The sample is one Premier League round and contains only 10 matches.
- Maximum prices can come from different bookmakers and do not represent one bookmaker's market.
- The source bookmaker set and recorded quotes determine the maximum fields.
- Opening and closing snapshots do not describe every price available between those points.
- Availability, stake limits and account-specific restrictions are outside this dataset.
- A lower book does not by itself identify a positive-expectation bet.
Data and reproducibility
The underlying odds are from the Football-Data.co.uk 2025/26 English Premier League file (E0). Betting Maths calculated the book percentages and changes. The derived CSV contains the opening and closing average, maximum and Bet365 fields used across this research series.
What this adds to the earlier study
The earlier opening-versus-closing article showed that a single bookmaker and the market average can behave differently. Adding the maximum-price benchmark makes that point stronger: there is no single universal “market margin” independent of which prices are selected. The measurement changes with the price set and the moment being measured.
