How Sportsbooks Set Lines: The Supply Chain from Pinnacle to Your Book
Most bettors treat the line as a given. It appears in the app, they bet it or skip it. Few ask where the number came from, who set it, and why.
The answer matters. The line you see at DraftKings or FanDuel is not the product of a team of oddsmakers analyzing your team. It is the end of a supply chain. Understanding that chain tells you when lines are soft, why they move, and which prices are worth acting on.
Two Types of Sportsbooks
Every sportsbook in the US falls into one of two categories: market makers or market followers.
Market makers set the price. They originate lines through genuine price discovery, run thin margins, and accept sharp action without restricting accounts. Their business model depends on volume and accuracy, not on exploiting uninformed bettors.
Market followers copy the price. They watch what the market makers post, add a markup for their margin, and react to line movement at the originating books. Their business model depends on attracting recreational bettors who do not shop lines.
The distinction is not cosmetic. It determines the quality of information encoded in the number.
Tier 1: The Market Makers
Pinnacle is the global benchmark. Operating offshore, Pinnacle posts the first line on most major markets, runs a hold of roughly 2-3% on NFL and NBA spreads, imposes no account limits on winning bettors, and allows six-figure wagers on major games. Its closing odds, measured across 397,935 European football matches, correlate with real-world outcomes at an r-squared of 0.997. That is the most efficient publicly visible price in sports betting.
In the US domestic market, Circa Sports runs a comparable model. Circa uses in-house oddsmakers who post independent lines rather than copying a third-party feed, posts early, and operates with higher limits than most domestic books. It is one of the few US books where the line you see is the product of actual handicapping, not vendor software.
These books serve a function beyond their own profit: they are the price-discovery layer for the entire industry.
How the Opening Line Gets Set
A sharp book does not open a game at full limits. Opening with $50,000 limits would expose it to a coordinated attack from professional bettors who have already run their models. Instead, market makers open at soft limits while the price is uncertain, then expand limits as sharp action confirms or corrects the line.
The low opening limits are not a restriction on bettors. They are a mechanism. By inviting sharps to bet small amounts into an uncertain line, the book uses their action as information. If a professional bettor sees the Patriots at -3.5 and knows they should be -4.5, they bet the Patriots. The book moves the line. Price discovery happens. The limit then expands because the book now has higher confidence the price is correct.
The Supply Chain
Once Pinnacle or Circa posts and adjusts a line, that price flows downstream through three channels.
DraftKings and FanDuel operate their own proprietary trading desks and do not use Kambi. But they still benchmark against Pinnacle's publicly visible lines and react to market movement at sharp books. Being independent of the Kambi feed does not make a retail book a market maker. It means they run their own variation of copying the market.
The practical consequence: most US retail lines are downstream of Pinnacle by minutes to hours. You are not getting an independently formed number. You are getting a marked-up version of a price someone else derived.
Steam Moves: The Market Correcting Itself
Steam moves are when the supply chain corrects at speed. A steam move is a sudden, uniform line shift across multiple books within minutes, driven by coordinated sharp action from a syndicate or professional group.
The mechanics are simple. A sharp group identifies a mispriced line at Pinnacle or Circa. They cannot bet enough at one book to move it meaningfully, so they send bets simultaneously to multiple outlets. The line at the originating sharp book moves. Retail books, watching that movement through odds feeds or monitoring tools, follow within seconds to minutes.
Steam is the information signal propagating through the supply chain in real time. A three-point steam move on a game an hour before kickoff is the market's way of telling you something changed. It is not random noise from public action.
Why Books Do Not Set Market-Clearing Prices
Steven Levitt's 2004 paper in The Economic Journal identified something counterintuitive about how US sportsbooks set prices. Standard economic theory says a bookmaker maximizes profit by balancing action and taking a clean vig. In practice, Levitt showed, books do not balance action. They shade lines toward bettor biases.
Using a dataset of 4,448 NFL bets from a single season, Levitt found that bettors won only 49.45% of their wagers instead of the 50% they would win under a balanced book. That 0.55 percentage-point distortion came from books setting prices that deviate from the true probability in the direction of where recreational bettors tend to bet. The result: bookmaker gross profits were 23% higher than they would be under a balanced model.
What this means in practice: the line you see is not purely the book's best estimate of the true probability. It is the book's best estimate adjusted for what direction bettors are likely to bet. Teams with large fan bases get shaded. Favorites get shaded. Overs get shaded. The line is the market's information signal plus the book's exploitation of your biases, stacked together.
At Pinnacle, this effect is minimal. The sharp bettor base punishes any deliberate bias immediately. At retail books with a recreational customer base, the Levitt effect is intact and deliberately maintained.
The Hold Tells You Where You Are in the Chain
The clearest indicator of a book's position in the supply chain is its hold percentage. Lower hold means thinner margins, which means the book is confident in its price and willing to accept informed action. Higher hold means fatter markup, which means the book is compensating for uncertainty or protecting against sharp bettors.
| Book | Model | Typical NFL Spread Hold | Typical Futures Hold |
|---|---|---|---|
| Pinnacle | Market maker | ~2-3% | ~3-5% |
| Circa Sports | Market maker (US) | ~4-5% | ~5-8% |
| BetMGM | Retail (Kambi feed) | ~8-10% | ~12-18% |
| DraftKings | Retail (proprietary) | ~9-11% | ~13-16% |
| FanDuel | Retail (proprietary) | ~9-12% | ~13-15% |
Massachusetts gaming commission data from April 2026 showed FanDuel holding 13.40% and DraftKings holding 13.12% on total handle. Those are not spread bets. Those are blended figures including parlays and same-game parlays, which carry a house edge of 20-35%. Strip out the parlay component and NFL spread holds at US retail books run 8-11%.
Pinnacle's 2-3% hold on NFL spreads is not a charity program. It reflects the cost of doing business when your customers include professionals who will punish any deliberate mispricing. The market forces thin margins. Retail books never face that pressure because they restrict accounts before it reaches them.
What Changes When You Understand the Chain
Three things follow directly from understanding the supply chain.
First, timing matters at different points for different reasons. Early in the week, sharp books post soft, uncertain lines. Retail books copy slightly later. If you have a strong opinion on a game, the opening window at a sharp book or a slow-to-react retail book is when mispricing is most likely. The closing line is the most accurate price, but you get worse odds to bet it.
Second, line movement has meaning only if you know the source. A two-point move at a retail book that is tracking steam from Pinnacle is meaningful. The same move in response to heavy recreational money on a popular team is not a signal about the true probability. Ask what caused the move before you act on it.
Third, CLV measurement requires using the right benchmark. Your DraftKings closing line is a downstream, marked-up version of a Pinnacle-originated price. If you want to measure whether your entry price was genuinely sharp, compare it to Pinnacle's close, not the retail book's close. The retail close is softer, and beating it does not tell you what you need to know.
Where Bettor Bias Enters the Price
Woodland and Woodland's 1994 Journal of Finance paper established that bettor bias creates persistent, measurable distortions in US sports betting markets. The favorite-longshot bias, documented in horse racing and various team sports, shows that bettors systematically overvalue longshots and undervalue favorites. Books know this and price accordingly.
In NFL spreads, the practical version shows up in home teams, popular franchises, and covers. Bettors bet the Patriots, the Cowboys, and the Lakers at rates that exceed their true probability, so books shade those lines to capture the imbalance without changing the book's actual risk.
Sharp money corrects these distortions at the market-maker level. When a mispricing is large enough, a professional bettor bets against it. The line moves toward true probability. By the time the price reaches a retail book, most obvious distortions are gone. What remains is the retail book's own added markup, not correctable by any bettor.
The One Thing Most Bettors Miss
The line is not the truth. It is the output of a system with multiple participants, each with different incentives. Pinnacle wants an accurate price because accuracy protects it against exploitation. Kambi wants a defensible price it can license at scale. Your retail book wants a price that attracts recreational bettors while limiting exposure to winning ones.
None of those incentives are aligned with giving you the fairest possible number. The number you see at the end of the supply chain reflects all those incentives stacked together. Understanding who made it, when, and why is the foundation of knowing whether the price is worth taking.
Shop lines across the supply chain rather than between two retail books. Use DraftKings, FanDuel, and BetMGM for the lines they happen to be slow to move. Watch Pinnacle for the line that reflects the best available information. Understand that a steam move at Pinnacle is more meaningful than a three-point swing at a retail book reacting to Sunday afternoon parlay money.
The supply chain runs in one direction. Knowing where you are in it changes every decision you make.