While we aren't exactly sure at which dollar amounts or what formulas sportsbooks use to determine when they shift the lines, we do know why they do it. It is their attempt to minimize their risk as much as possible and guarantees sportsbook profit. Lines will also move if something major happens (like Lebron breaking his leg or something) so keep an eye out for this. Ultimately, the shift in the line is done for the exact same reason to keep the same amount of money on both sides of the game. As you'll see in the strategy and tips section, shifting lines do present some interesting opportunities for sports bettors.
For example, imagine a game where the odds were -550 for the favorite and +450 for the underdog. A bettor shopping around for lines might be delighted to see the same favorite offered at -490 and enthusiastically back the team at those odds simply because those are the best odds available. However, if we removed the vig from -550 and +450, we'd see that the fair odds are actually -466 and +466. So, placing a wager at odds of -490 doesn't actually offer any value.
So to solve the first fraction for the Heat, we do 13 divided by 20 and get 0.65. Let’s look at our calculations for the $10 bet and the $250 bet. If we bet $10, we multiply our solved fraction of 0.65 by $10 and get $6.50. This is our correct profit! If we bet $250, we multiply our solved fraction of 0.65 by $250 and get $162.50. This is out correct profit!
These bets are extremely popular and a lot of fun to make. They allow you to bet on teams that you want to root for, but you know they aren't going to win the game outright. It all comes down to betting on how you think the team will perform in regards to what the sportsbook thinks. If you can find teams that you think the sportsbook is undervaluing or overvaluing, you can make a lot of money by betting on your findings.

Conversely, in most other countries financial spread betting income is considered taxable. For example, the Australian Tax Office issued a decision in March 2010 saying "Yes, the gains from financial spread betting are assessable income under section 6-5 or section 15-15 of the ITAA 1997".[6] Similarly, any losses on the spread betting contracts are deductible. This has resulted in a much lower interest in financial spread betting in those countries.
We went into detail earlier about what causes moneylines to move. The better you can get about predicting when these movements will occur and in what direction, the more profitable you’re going to be as a sports bettor. If you find a bet that you like, but you predict it’s going to move more in your favor, you can intelligently wait to bet and lock up a potentially much more profitable opportunity.
We mentioned we would touch on the -3500 bet in this section. If you calculate the implied probability of -3500, you see that it is 97.2%. This means that the bet will have to hit 97.2% of the time for you to break even. Now, if you think that the bet is actually 100%, then it might be a smart bet to make. You’re still going to have to put up a lot of money to see any real sort of profit, which might not be desirable based on your personal preferences.

If all the money at one sportsbook comes in on Team A and all the money comes into a second sportsbook on Team B, they’re both going to adjust their lines accordingly to what is going on in their book. This means that if you want to bet on Team A, you should go to the second sportsbook where the line will be great. If you want to be on Team B, you should go to the first sportsbook where the line will be better.
Sports betting has been around since 1000 B.C in China, where betting on animal fights was commonplace. In ancient Rome, one could wager on the Gladiatorial games. The idea of betting on sports is as old as organized sport itself. But up until the 1940s, bettors were fairly limited in what kind of bets they could make. The standard system of odds would allow bets on, for example, the 3-1 odds that the Steelers would beat the Browns.
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