A single bet combining multiple selections — all must win for the bet to pay out, with each successive win multiplying the potential return.
An accumulator (or acca) is a single bet that links two or more selections together. The winnings from each selection roll over and become the stake for the next. All selections must win for the accumulator to pay out — a single loser kills the entire bet.
A four-fold accumulator with selections at 1.80, 2.10, 1.60, and 2.00 has a combined odds of 1.80 × 2.10 × 1.60 × 2.00 = 12.10. A £10 stake returns £121 if all four selections win.
Accumulators are poor value relative to placing the same bets individually, because the bookmaker's overround is compounded across each selection. A four-team acca with a 5% margin on each leg has a combined 19%+ edge against the bettor.
Despite this, accumulators remain popular due to the appeal of large returns from small stakes. For value bettors, keeping acca legs to only genuine positive-EV selections (rather than filling with near-certainties at poor odds) improves expected value.
Overround (Vig / Juice)
The bookmaker's built-in profit margin — the amount by which the implied probabilities of all outcomes in a market sum to more than 100%.
Expected Value (EV)
The average outcome of a bet over a large number of repetitions — positive EV means the bet profits long-term; negative EV means it loses.
Implied Probability
The probability of an outcome embedded in bookmaker odds — calculated by dividing 1 by the decimal odds.
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