Updated: Mar 17, 2016
In many sporting events including horse racing as well as with individual sports such as tennis, bets placed well in advance on sports betting sites can be particularly subject to changes in odds.
A strained muscle or a bad showing in practice in the days leading up to the event can dramatically shift betting patterns and the odds that drive them, but understanding the way bookmakers constantly adjust odds can help you turn the system in your favor.
Fixed Odds Betting
With a fixed odds bet, the odds displayed at the time the wager is placed is guaranteed for as long as the bet is valid. Although the odds may be subject to change for later bettors, a bet placed at 7-to-1 odds will be paid out at that rate if successful even if the listed odds horten significantly.
Fixed odds bets are only available for certain event types, and are not used at all with exotic bets including horizontal betting, vertical betting or many kinds of prop bet.
In contrast, parimutuel bets are subject to sudden and substantial fluctuation due to any number of factors. With a parimutuel bet, also called a totalizer or “totes” bet, the odds displayed at the time of the wager are a representation of what you can expect to win if your wager wins. This is because this type of bet is paid out from a central pool of wagers to be distributed to all other wagerers who made the same prediction, making it closer in style to a common lottery for odds making purposes.
Why Odds Change
Odds can shift for many reasons, but the most common reason is an unforeseen circumstance befalling one or more of the competitors in an event. For example, two evenly matched fighters may draw fairly equivalent betting for weeks before the match, guaranteeing a profit for the bookmaker who receives equal revenue from both sides of the wager.
However, occurrences such as minor injuries or a lackluster training camp from one of the combatants may hurt the public perception of his chances in the fight, leading to unbalanced betting on his opponent. To offset this imbalance and protect the bookmaker from undue risk, the odds will be shortened on the favored side to offer a more attractive wager for potential bettors on the other side. This often presents a unique opportunity for savvy gamblers, as they can anticipate the effects that news for either fighter will have on their betting odds and quickly place bets at odds favorable to the player before they are adjusted.
Odds can be somewhat unstable well in advance of the event, but changes in them often indicate significant developments that fundamentally change the likelihood of each outcome. Fixed betting is a way to guarantee the details of your wager, but closely monitoring updates regarding events and taking advantage of promising odds is an effective way to make parimutuel betting consistently profitable as well.