What is line movement? How does it work?

It usually happens as a result of money, news, and injury reports.

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In sports betting, line movement describes when the odds or point spread for a game changes from the time the bet opens to the time the game starts. For purposes of this article, line movement is any pre-game change in odds.

Recognizing line movement, and more importantly – knowing how to project line movement – will help you get the best possible price on your bets and give you valuable insight into navigating the world of sports betting.

In this article, we will analyze the topic of line movement and understand what a betting line is. We will learn why a sportsbook sets a line and why a line moves. We will then look into some advanced strategies surrounding line movement and look at specific examples from different sports to illustrate how to best bet moving lines.


Betting lines and why they move

To understand line movement, we need to first understand what a betting line is. The betting line can refer to any type of bet – a point spread, a moneyline, or an over/under total.

Sportsbooks set betting lines with the intent of maximizing their chance to make a profit, usually by moving lines as money comes in on a particular side of a bet. Sportsbooks need to balance the amount of money being placed on each side of a betting line, and dictating line movement is their best attempt to hedge exposure and maximize profits.

Let’s take a hypothetical NFL point spread to illustrate how a line can move from the opening of a betting line to the kick-off of the game.

Opening Line:

  • Baltimore Ravens -3 (-110)
  • Dallas Cowboys +3 (-110)

In this hypothetical, the Ravens open up as 3 point favorites against the Cowboys on Monday morning. The -110 refers to the “juice” on the bet – in this case, a $110 bet would win back $100. (If you want to read more about juice, or “vig”, as it is also commonly called, you can do so here.)

The game is set to take place on Sunday. You’re thinking of placing a bet on the Ravens, but maybe your bankroll isn’t where you want it to be. You decide to wait. On Sunday morning, you return and find that the line has moved.

Sunday’s Line:

  • Baltimore Ravens -5.5 (-110)
  • Dallas Cowboys +5.5 (-110)

This same betting line, six days later, has moved 2.5 points. If you still want to bet the Ravens point spread, you now are missing out on two very important key numbers (which we will discuss later in this article) in 3 and 4 – and the line movement has worked against you.

What caused this line to move? The most common answer is that the sportsbook is likely taking more money on the Ravens than they are on the Cowboys, and they want to entice people to bet on the other side. The general rule of thumb is that favorites attract more bets, especially from the general public.

There also could have been a negative story about the state of the Cowboys locker room leaked in the media, or a few key defensive players could have been ruled out for the Cowboys.

Line movement usually happens as a result of the following three things – money, news, and injury reports.

Reacting to line movement is an essential tool for a bettor. It gets easier to react to line movement as you become more experienced and, as time goes on, reading lines and projecting line movement will become second nature to you.

What is line movement?

When to bet and how to bet line movement

Since we now understand that line movement most commonly occurs when a large majority of the money is bet on one particular side, knowing when to bet a certain team or number is key to maximizing your chances of winning bets. 

So when should we place bets, knowing that lines move? As a general matter, try to bet on favorites early. Underdog odds tend to improve as the game nears, so consider waiting to bet on them if you don’t particularly like the price at the moment.

Personally, in betting the NFL, I love to bet early lines. I’ll take a look at other external sources to project games and lines – like DVOA, an advanced efficiency metric calculated by Football Outsiders – and try to identify discrepancies. If I think an opening line is fishy and have a good feeling that the line will move in a certain direction, I’ll jump on the early line. Getting a full point or two in NFL games can prove to be huge, especially if the line moves over certain key numbers, which we will discuss a little later.

Timing is everything, especially in certain sports where a single player’s injury is worth multiple points in a betting line. This timing is key in both football and basketball.

If an NFL quarterback is listed as questionable or doubtful during the week, and is later ruled out by kick-off time, the line can move a full field goal or touchdown.

In the NBA, the rise of teams utilizing rest for certain stat players (think Kawhi Leonard and “load management”) has led to huge point swings from the original betting line to the opening tip-off in regular season games.

Monitoring injuries is key to betting all sports, but absolutely crucial to betting NBA games in the regular season. A great NBA bettor I trust recommended that I follow an injury reporting service like Fantasy Labs to get notifications as soon as a player is ruled out. The point spread swings can be massive. Sometimes, if you are quick, you can get bets in minutes before a sportsbook becomes aware of the injury and changes the line.

Always keep in mind that line movement is fluid. What looks like a great play in the morning can seem disastrous by the time evening rolls around. Remember to make sure you understand why a line is moving in a certain direction, or what could make a line move in a certain direction, before placing a bet. 

Dramatic line movement can indicate “sharp” money, and is a key factor in knowing and understanding line movement. We will take a look at these big moves now.

Baltimore Ravens quarterback Lamar Jackson (8) advances against the Tennessee Titans during the first quarter of a NFL Divisional Playoff game at M&T Bank Stadium Saturday, Jan. 11, 2020 in Baltimore, Md. An54201

Sharps versus the public – and how a certain side can project line movement

In sports betting, a “sharp” is referred to as an individual bettor or a group of bettors who are taken very seriously by sportsbooks. These bettors wager large sums of money on games and view their wagers as investments, rather than casual bets. When the term “sharp money” is used, it usually refers to the side of a bet line that the experts are betting on. As a result, knowing what side the sharps are betting can give you valuable insight on projecting line movements.

Contrast sharps with the “public”. The public is defined as bettors who casually bet on a game. Sportsbooks and oddsmakers are well aware of the tendencies of casual bettors, and the general rule that they like to bet on favorites and the over on game totals. As a result, sportsbooks will provide more favorable lines for the side that’s likely to entice more wagers from the public.

Betting percentages are key to knowing what side of a bet is public (indicated by which side has a greater percentage of the bets placed) and which one is backed by sharps (indicated by which side has a greater percentage of the money placed on a particular side).

There are plenty of tools available to track the number of tickets on a certain side of a bet, along with the amount of money as a percentage of the number of bets, that can indicate sharp plays to get ahead of line movement in your favor. The Action Network is one service I use to track these numbers.

Reverse line movement 

Reverse line movement is a prime example of the nuance surrounding the shifting of odds. For example (using the NHL this time), let’s say the Toronto Maple Leafs moneyline is listed at -200 against the Montreal Canadiens, with 78% of all bets being placed on the favorite Maple Leafs. Your first inclination could be that the line will move to -210 or -220, but instead the Maple Leafs moneyline drops to -180. This is called reverse line movement.

If a line moves in a different direction than expected, it is most likely because there was a greater percentage of money placed on the other side. Even though in the above hypothetical 78% bets were placed on the favorite, it is possible that only 25% of the money wagered in total was on the favorite. The sharps are on the underdog Canadiens. As a result, sportsbooks are forced to adjust the line in order to entice a larger percentage of money on the other side.

How should we react to reverse line movement? In general, the rule of thumb is to fade the public. Sharp bettors have a long track record of success, and although they do lose bets, they by and large win more bets than they lose. One of the easiest ways to follow sharp action is to follow reverse line movement. However, you can maximize profit by being on the side of sharps before the line moves to adjust to them. In the hypothetical outlined above, betting the underdog at +7 before the line moves to +6.5 could maximize your potential of placing a successful wager. 

Advanced line movement betting strategies

There are a few more common betting strategies surrounding line movement that we will discuss. These strategies – middling, playing key numbers, and buying points – are all important to maximizing your profits in the world of sports betting. 

Middling

The first strategy we will discuss is “middling”, one of the most common ways to take advantage of line movement. By definition, middling means betting both sides of a bet when the line has moved significantly, leaving a “middle” outcome where you can win on both sides. 

We will look at a quick example to illustrate middling, this time using the NBA. Let’s say the Celtics are playing the Lakers, and the line opens up like this:

  • Boston Celtics -1 (-110)
  • Los Angeles Lakers +1 (-110)

Let’s say you’ve decided to bet $110 on the Celtics at -1. A few hours before the game, a key Laker is ruled out, and the line moves heavily towards the Celtics:

  • Boston Celtics -7 (-110)
  • Los Angeles Lakers +7 (-110)

As a bettor who has already bet on the Celtics at -1, this new line gives you a prime opportunity to bet the Lakers at +7 and “middle” the game with a chance to win two bets. So you decide to bet $110 on the Lakers +7. Now that you have both Celtics -1 and Lakers +7 tickets, you can win both bets if the Celtics win by anywhere from 2 to 6 points, netting $200 profit. If the Celtics win by 1 or 7 points, you win one bet, and push the other, netting you $100 profit. And in the worst case scenario, you win one bet and lose the other, forfeiting a mere $10 in total bankroll. 

Only to be considered when a line moves more than a few points, middling can be used to both maximize your profits on a particular bet or hedge against a loss.

Playing key numbers


The second strategy we will discuss is playing key numbers. Key numbers are much more relevant in football (and to a lesser extent, basketball) than they are in other sports with fixed runlines or pucklines like baseball and hockey. 

Key numbers in football (especially in the NFL) are very important. Key numbers are numbers that, more often than not, end up being the score differential that a game hinges on. Given that a touchdown and an extra point is worth seven points, and a field goal is worth three points, the key numbers in football are 3 and 7. Think about Super Bowl box pools – you’re probably happy to find you have these numbers when they are drawn. These key numbers are crucial to betting NFL point spreads.

Per Wizard of Odds, a 3 point margin of victory occurs 14.5% of the time. A 7 point margin of victory occurs 9.2% of the time. A full table can be found on their page, which uses data from 2006 to 2018, but it is safe to say that 3 and 7 are the biggest key numbers in the NFL. 4, 6 and 10 are other important numbers.

If you want to bet an NFL underdog with the points, a line of +4.5 is worlds better than a line of +2.5, given that a score differential of 3 or 4 points in an NFL game is much more probable than a score differential of 2. Knowing where the line is going to move is essential to playing key numbers and getting good prices on your bets.

Buying points

The third strategy we will discuss in the world of line movement is buying points. Buying points allows the bettor the option of moving the point spread or totals in your favor when betting on football or basketball. When betting favorites, buying points allows a bettor to take off a half point, a full point, or 1.5 points. And when betting underdogs, a bettor can add a half point, a full point, or 1.5 points. 

Sportsbooks vary in the price of buying points, but the general rule is that a half point is worth an extra ten cents in juice. In our earlier NFL example, if you wanted to buy points with the Ravens -5.5 (-120), you would pay -120 to buy them down to -5.

Knowing and playing key numbers is also crucial to buying points, and sportsbooks know this. Most sportsbooks will charge twenty-five cents as opposed to ten cents when buying on or off key numbers of 3 or 7. 

Being able to project line movement will help you buy points in a certain direction away from line movement. For example, if you think the Ravens -5.5 will start to creep up to -6, buying points in the opposite direction before the line moves will increase the probability of a winning bet.

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