What is Line Movement? – Balancing a Market

The Line Defined

Before looking at line movement, we need to be clear what we’re talking about when we refer to “the line”. Any game or match-up will have three main “lines”, which cover the three main types of sports bet.

1. In Moneyline bets, you back either the favorite to win, or the underdog to cause an upset. As you should know by now, when using American odds, the favorite carries negative odds (e.g., -250), and the underdog positive odds (e.g., +200). In a Moneyline bet, this is the line.
2. In a Point Spread, the line is simply the size of the spread. The favorite, at -9.5 has to win by 10 to cover the spread. The underdog can still lose by up to 9 points to cover the spread. The line on the spread is 9.5.
3. For an Over/Under on a Totals bet, the line is the Totals number. In the NFL the line might be, for example, Over/Under 43, while in the NBA it could be Over/Under 215.

A Sportsbook’s Dream – A Balanced Market

From the sportsbook’s perspective, an ideal world – or at least, operating environment – is one where the line on a game attracts equal money on both sides.

In a Moneyline, where the risk in backing the underdog is matched perfectly by the payout (i.e., the odds), yet the odds on the favorite are equally as attractive. Or where a Point Spread so perfectly captures the difference between the two sides that it’s impossible to decide which side to take.

In other words, the dream is a line so perfectly balanced that bettors see value in both sides.

Why? Because this way, regardless of which way the result goes, the book makes money.

If the underdog surprises, money taken on the favorite covers the liability; and vice versa should the favorite win. And because the sportsbook takes vig on all bets, it is guaranteed to make money.

Of course, the reality is vastly different. Enter line movement.

A Sportsbook’s Reality – Balancing the Market

Back in the real world, a bookmaker’s opening lines are always fluid.

From the opening odds when the line is first set to the closing odds, there is potential for significant movement. The extent of that movement also depends on how sharp the initial market is.

In mainstream sports like the NFL, NBA, MLB, NHL and major soccer leagues around the world such as the English Premier League (EPL), Italy’s Serie A, or Germany’s Bundesliga, you can expect line movement to be somewhat more limited, or at least less severe.

In niche sports such as MMA, for example, there may be more scope for bigger swings if the gambling community reacts strongly against the sportsbook view.

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An Example of Line Movement in Action

Action often drives line movement, but it is not the only factor to account for. Team news, player updates and even the weather report can play a role.

Let’s start with a hypothetical football moneyline set at a very wide -650 on the favorite and +500 on the underdog. Let’s assume the line opens three days ahead of the game.

• At -650, you need to wager $650 on the favorite to win $100.
• At +500, a $100 bet on the underdog would win you $500, for a $600 payout.

As the odds weigh so heavily towards the favorite, it is also safe to assume that this hypothetical deserves a fairly wide Point Spread – let’s say a rather generous 10.5 points. There’s also potential for this to be a one-sided blowout, so the Total Over/Under is 48.

The game lines open like this:

• Moneyline: -650/+500
• Point Spread: 10.5
• Total: O/U 48

Once the lines open, however, it becomes apparent that the betting public disagrees with the extent to which the favorite is favoured. The majority of action (80/20) goes to the underdog.

The bookmaker now has to make the underdog position less attractive, and the favorite position more attractive, to encourage action that will help it balance the market and limit its liabilities if the underdog wins or covers the spread.

To do this, it moves the lines.

Narrower odds, a tighter spread

Moneyline odds narrow in from -650/+500 to -550/+400. Now, backing the favorite requires you to risk $100 less, while backing the underdog wins you $100 less. The spread might also narrow, to 9.5 points, making it easier for the favorite to cover. The bookmaker sees a shift in the betting patterns and these line movements are having the desired effect. For the time being, the book can leave the Totals line as is.

The market starts to rebalance, but action is still 65/35 toward the underdog. There are still two days until the game.

A day before the game, news breaks that the underdog’s one shining light, it’s rookie star wide receiver, skipped leg day last week and has tweaked a hamstring. It’s uncertain if he’ll play on Monday night.

To the sportsbook’s glee, action starts to pour in on the favorite so it can move its lines again.

This time, however, it doesn’t have to do much to make the favorite position more attractive, as the question mark over the WR has done that. However, moving the odds to -450 is a sure-fire way to attract more action.

The spread at 9.5 is now looking tougher for the underdog to cover. The book could bring it down to 9, but to avoid a potential push, moves it to 8.5 points. The line movement keeps the action alive ahead of kick-off.

Odds on the spread shift from -110

To entice backing of the favorite on the spread, it also tweaks the odds from -110 both sides to -105 of the favorite and -115 on the underdog.

The Totals line can be tweaked too. Without their star receiver, the underdogs look less likely to score at all, while the favorites seem keen to protect their big-name players once a win looks like it’s in the bag.

As such, the Over/Under drops substantially to 38. The Over may now look attractive to some. Overall, the bookmaker is now far happier about how the ledger looks going into the game.

Line	Opening Odds	Closing odds	Line Movement
Moneyline	-650 / +500	-450 / +400	+200 / -100
Point Spread	10.5 (-110/-110)	8.5 (-105/-115)	2 (+5/-5)
Total (Over/Under)	48	38	10

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Timing your bets

Comparing the two sets of odds you can see how timing your bets can have an impact on your betting career over time. If you like the underdog, you’d have done well to bet early, locking in the higher odds. If you like the favorite, the opposite holds. The favorite on an 8.5 spread is a much better bet than at 10.5, and even costs you less to lay. On the Total, Under 48 may have looked good, but now Over 38 looks far more handsome.

As with most things in life, you tend to find you improve the more you do it and the more comfortable you begin to feel in that environment. Sports betting is no different. over time, learning to judge line movement – and act accordingly, depending on your view – becomes easier to do.

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Reverse Line Movement

Line movement, as described above, does not however always move to the popular side. On occasion we may see a line move towards a team that is already garnering most of the action. This is reverse line movement.

For example, Tampa Bay have a -10 point spread against the Giants and see 75% of the action.

The spread then drops to -9, which is highly counterintuitive as the money coming in suggests Tampa Bay can easily cover 10.

Why would this happen?

Sharp impact

Reverse line movement like this is almost always attributable to large amounts of sharp money layed on the other side.

Because sharps are respected by sportsbooks, a significant amount of sharp money on the other side may be enough to convince a sportsbook to shift it’s line.

Steam Moves

A “steam move” is when there is a sudden, drastic line move not just at one book, but across the whole sports-betting landscape. This usually reflects sharp bettors placing large amounts on the same bet across numerous sportsbooks simultaneously.

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