Sportsbooks earn money using what’s commonly referred to as the “vig.” The vig is built right into the odds on every bet. As long as they take in an equal amount of money on each side of a bet, sportsbooks will earn the difference between what they take in on the losing side and what they pay out to winners. This is the vig.
It makes no difference to the sportsbook whether you win or lose, just that they take in an equal amount of money on each side, giving them the chance to earn that vig. That means sportsbooks are always trying to keep the betting even.
In other words, when more money is coming in on one side of a bet, sportsbooks will move the line to try to make the other side more attractive. This will draw more bets on that side, getting things back to even.
Keep reading for an in-depth analysis of why sports betting lines move, what lines see more movement, and the different ways you can take advantage.
Equal opportunity sportsbooks
Sports betting is a business. Sportsbooks are the service providers in this business. They’re not the ones gambling; you are. As long as they can draw equal betting action on both sides of a bet, they’re earning the vig built into the odds. When they can do that, sportsbooks aren’t sweating the outcome of a game like you are, and they don’t care whether you win or lose.
Let’s say a North Carolina online sportsbook draws $110,000 in bets on the Carolina Panthers at -3.5 (-110) and an equal $110,000 on the New Orleans Saints in the same game at +3.5 (-110). If Carolina covers, they’ll pay out $100,000 in winnings to anyone who bet on the Panthers, but they’ll keep the $110,000 bet on the Saints. That $10,000 difference is the vig they’ll earn.
However, sportsbooks are at risk when more money comes in on one side of a bet. Let’s say a NC sports gambling site draws $110,000 in bets on the Carolina Panthers -3.5 (-110) and just $55,000 on the New Orleans Saints in the same game at +3.5 (-110). If Carolina wins by four or more, the sportsbook will lose $45,000, paying out $100,000 in winnings to anyone who bet on the Panthers, but only keeping the $55,000 from bets on the Saints.
That’s not a sustainable business model. Let’s learn more about how sportsbooks approach such a situation below.
They’ll try to avoid that risk by moving the line and making the Saints a more attractive bet. The goal is to draw another $55,000 in bets on New Orleans and get the betting back to even. To accomplish that goal, they might move the line to Saints +5.5 (-110).
If they can get things back to even, sportsbooks will collect on the original vig built into the odds, avoid the risk, and earn their money by providing a betting service to you, not gambling.
The difference in the amount of money bet and the size of the risk involved determines how much a sports betting line will move. Plus, since different sportsbooks see different action, a line might move one way at one sportsbook and another way at a different one. This type of line movement is just an effort to try to get the betting back to even on both sides of a bet, and it is restricted to the specific book that’s seeing the increased activity on one side or the other.
What is reverse line movement?
Those familiar with the term KYC (Know Your Customer) know the best service providers practice it. KYC is about service providers understanding their customers and tailoring the service to fit customer needs.
For sportsbooks, KYC takes on a different form. We know that more money bet on one side of a wager forces sportsbooks to move a line, trying to get betting back to even. But if all the smart money, the money from the sharp sports bettors who win more often than anyone else, is coming in on the other side, sportsbooks may have a different reaction.
Sportsbooks know their customers. They look at who is betting as closely as how much is bet. They’ll move a line the other way if the sharpest bettors are all on one side. This is referred to as reverse line movement.
Let’s say a North Carolina online sportsbook draws $110,000 in bets on the Carolina Panthers -3.5 (-110) and just $75,000 on the New Orleans Saints at +3.5 (-110). However, the book sees that all the bets on New Orleans are coming in from expert bettors.
Even though this sportsbook stands to lose $25,000 if Carolina covers, they may move the line the other way, fearing that the sharps know something they don’t. When they see the winningest sports bettors on the platform heavily backing one side, they’ll think that side is more likely to win.
In this case, they might move the line on the Panthers to -1.5 (-110) trying to make Carolina more attractive to the rest of the betting public. Sportsbooks know their customers and respect the opinions of sharp bettors that much.
Line movement in NFL, NBA, MLB
No matter the sport or the line, sportsbooks will move it if betting is uneven. However, some sports and bets see more movement than others.
NFL spreads see the most line movement in sports betting simply because these are the most popular lines at any book. NFL totals and even moneylines will also move.
NBA spreads also move quite regularly, as will NBA totals and moneylines. However, in the NHL, MLB, and MLS, you’re more likely to see alternative spreads at different odds available than you are to see the puck line or run line move.
Tracking line movement and betting against the public
You can track line movement simply by watching how an opening line moves at NC online sportsbooks. It’ll mean waiting for a few days, up to a week, before placing any bets on a line, to see if there’s any movement.
Oddsmakers set lines with great accuracy, especially when it comes to the NFL. Knowing that means you can take advantage of line movement.
Let’s say a North Carolina online sportsbook draws $55,000 in bets on the Carolina Panthers -3.5 (-110) and $110,000 on the New Orleans Saints at +3.5 (-110). They might move the line on Carolina to -1.5 (-110) to try to get the betting back to even.
With this new line, you can more confidently bet on the Panthers, knowing oddsmakers still think Carolina will win by a field goal or more and you only have to give a point-and-a-half.
Let’s say a North Carolina online sportsbook draws $110,000 in bets on the Carolina Panthers -3 (-110) and $55,000 on the New Orleans Saints at +3 (-110). They might move the line on New Orleans to +4.5 (-110) to try to get the betting back to even.
With this new line, you can more confidently bet on the Saints, knowing oddsmakers still think Carolina will win by a field goal and you’re getting 4.5 points.
In both cases, this is called betting “against the public” because you’re banking on the accuracy of the original lines, not where the first bettors wanted to put their money.