Glossary · Bookmaker margin (overround)
Bookmaker margin (overround)
The commission the operator builds into the odds. It makes the implied probabilities of an event add up to more than 100%; that excess is its expected profit.
Example
Odds 1.90 / 1.90 imply 52.6% + 52.6% = 105.2%: a 5.2% margin.