Fixed-odds betting – Wikipedia

It is customary with fixed-odds gambling to be aware of the chances at the time of the placement of the wager (the“live cost“), however, the group also includes wagers whose cost is determined just when the race or match starts (the“starting prices“). It’s ideal for bookmakers to price/mark up a book like the outcome will always be in their favour: the sum of the probabilities quoted for all outcomes will be in excess of 100 percent. The surplus over 100 percent (or even overround) represents profit to the bookmaker in the event of a balanced/even book. In the common case of an publication that is imbalanced, the bookmaker may have to pay out winnings than what is staked or may earn greater than mathematically expected. An imbalanced book may emerge since there is no way to get a bookmaker to know the true probabilities for the results of contests left to individual effort or to predict the stakes that will be drawn from others by fixed odds compiled on the basis personal view and comprehension.
With the advent of Internet and bet exchange betting, the possibility of fixed-odds arbitrage actions and books against bookmakers and exchanges has enlarged. Betting exchanges particularly act like a stock exchange, allowing the chances to be put in the course of trading between individual bettors, usually leading to quoted odds that are reasonably close to the“true odds.“

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